Full file at http://testbank360.eu/solution-manual-conceptual-integrated-science-2nd-edition-hewitt

The Student-Centered Class

A great lecture is one where central information is concise and clearly explained, and when appropriate, with demonstrations. The students value such a lecture because clear explanations are what they are there for. A not-so-great class is one where the instructor covers peripheral information, not central, and not clearly explained. Poorly executed demonstrations do little to make the fix. Either way, in traditional classes where lectures are the main focus, the students remain seated with pen and paper taking notes to be studied in more detail later.

The traditional class format can be effective, at least if we are looking at short-term goals. Educational research suggests, however, that better results are obtained when the instructor makes the students active participants. Check-Your-Neighbor type questions are a good starting point for active participation. This is where you as the instructor ask a question of the class and students discuss possible answers amongst themselves.

You can take this interactive approach a step further by allowing students to use class time to collaborate on projects, worksheets, or hands-on activities. Collaborative, student-centered learning can be achieved through various teaching strategies. For example, students can be asked to do the science demonstrations themselves and asked to explain the underlying concepts. Any lecture presentation you provide can be short and sweet, and provided “on the fly” in response to students’ specific needs as revealed by the demonstrations. In such a scenario, students are in the spotlight. They find that class is akin to a grand study session where the instructor is their study leader, who migrates from team to team providing expert assistance on demand. This is the essence of the “student-centered” class. Lectures are minimized for the sake of increased class participation.

Students Must Come PreparedThe prerequisite to an effective student-centered class is that the student arrives to class prepared. Assignments need to have been read beforehand and exercises attempted beforehand such that a hazy understanding has already begun to take form. But as any instructor knows, student resistance to coming to class prepared can be intense. How then do we motivate students to come to

Full file at http://testbank360.eu/solution-manual-conceptual-integrated-science-2nd-edition-hewittclass prepared? There are numerous tools. First of all, it is vital that the textbook be as user-friendly as possible—students should enjoy reading it! This, of course, has been one of the main goals in developing the Conceptual Integrated Science textbook. The student should be able to learn about science concepts on his or her own with minimal assistance from the instructor—and it should make good reading! This, in turn, supports the instructor who is wishing to move toward a student-centered class.

Another important tool for encouraging students to study is a short quiz given at the beginning of class, or even before class with the quiz posted on the course website. This quiz should assess students for their familiarity, not their expertise, of the material about to be covered. Following the quiz and a brief introduction, students work on various activities within teams. If a student comes ill-prepared, he or she then faces the motivating factor of peer pressure. Of course, not everyone can always come prepared. Students know this and are generally forgiving and welcoming of all input either weak or strong. So peer pressure needn’t be unkind.

If you are ready to make your classes more student-centered, you need to let your students know at the beginning of the semester how this approach will help their learning, provide for an enjoyable experience, and, ultimately, improve their test scores. Notably, the interpersonal skills gained through collaborative learning is an added plus. Also, students are much more willing to participate if the in-class activities are unequivocally related to the quizzes and exams they take.

Lastly, a student-centered approach consumes a large portion of class and so the instructor has less opportunity to deliver content, though a greater opportunity to facilitate the learning of content. Consequently, in order to keep pace with a traditional syllabus, the instructor needs to decide whether there will be material on exams not covered directly in class. If so, the instructor should be mindful to reserve class time for the more challenging concepts.

Students Are the Players and You Are Their CoachThere is great pedagogical potential in transforming a class from passive learning to active, student-centered learning. To achieve the potential, what is needed is a willingness to get creative and to push the responsibilities of

Full file at http://testbank360.eu/solution-manual-conceptual-integrated-science-2nd-edition-hewittlearning more squarely on the student. The role of the instructor is to provide students with good questions rather than good answers. We can think of students as team players out on the field doing all the hard work, which means finding answers for themselves. We are their coaches here to direct their learning efforts. Sometimes the best way to do this is by knowing when to cheer and when to remain silent.

Getting StartedSo, is it better to retool one’s teaching methods in a single semester or to explore new activities one at a time over many years? Revolution or evolution? If you’re like most of us, the thought of revamping everything within a single semester is most undesirable. Indeed, implementation of any student-centered activity requires a fair amount of trial and error. Imagine implementing many new activities all within a few weeks only to have them fail miserably. This would be a disservice to your students and to yourself. The best practice is to introduce only the activities you think will work in a time frame that allows for successful development.

The techniques presented here are a select few that we authors know work well. Some work for large classes while others are better suited for smaller classes. Chances are that you have already implemented techniques of your own or that new ideas will soon be coming to you as you forge ahead. Also, you need look no further than journals, such as those of the National Science Teachers Association or through the web to find a constant flow of student-centered learning innovations. Some references are included at the end of this essay. The point to be made is that student-centered learning can be implemented profitably even by teachers who have had great success with lecturing.

Student-Centered Assessment Techniques(What students can do to articulate what they think they’ve learned)

We give homework, quizzes and exams so that we can provide students with a grade. But there is another important reason for these assessment tools, which is to provide students with feedback on their learning. Interestingly, assessment and grading need not be paired. So if you’re looking for a stress-free, non-penalizing way to support your students as they struggle to learn, consider providing “suggested homework”, “practice quizzes”, “practice exams”, and even “practice worksheets”. To show you appreciate the great value of practice (as would any coach, including an academic coach), let your students do these practice activities right during class where you’ll be personally available to offer assistance to individuals and to teams. Students appreciate the opportunity to practice, which is why we say: assess often, grade only when needed.

The Concepts InventoryThe Concepts Inventory is a short test taken by students at the beginning of the semester and definitely not graded. In fact, you might consider having the students take the test anonymously. At the end of the semester, the Concept Inventory with the very same questions is given again to provide a semi-objective measure of overall student learning. This is an assessment not only of the students but of the course as well. Inventory questions should reflect concepts that you hope the students will learn by taking the course. A good inventory will also include questions that address common misconceptions. Rather than giving the inventory again at the end of the semester, you might consider sneaking the questions (some or all) into the final exam.

EOC ExamsAt the end of each chapter (EOC) of Conceptual Integrated Science are numerous questions. These are provided so that students can practice applying the concepts they think they have learned. But of course, many students tend not to work on these questions unless they are assigned by

the instructor for homework, usually just a selected few. As an alternative, students can be given a longer list of each of the instructor’s favorite EOC questions that are applicable to the course syllabus. The students are then told that a certain number of these questions will definitely be posted on an upcoming exam. Keep in mind that only the answers to the odd-numbered EOC questions appear at the back of the textbook. Also, many of these EOC questions can be found in multiple-choice format within the Conceptual Integrated Science test bank.

The Minute QuizAs said, a quickie quiz given at the beginning of class it is a valuable component of your course. Their purpose, as said, is to motivate reading material for the day before class. Call them “minute quizzes” because the students have only one minute to answer a question that calls for a word or very short sentence. They can pass their quizzes to the front of the room, or put into boxes passed around the class. If you have the time and motivation to grade and record responses, good for you. But as said, even if you tell the class that you’ll not look at every day’s quizzes, and you won’t record scores, the process still works! Students don’t like handing in blank papers!

The Two Minute QuizThe minute quiz described above can be extended in to two phases. For the first phase, students get about a minute to answer the question, which may be printed on a narrow strip of paper. They can put their answers into a box that gets passed around the class. A right answer is worth, say, 25 points while a wrong answer is worth 10 points. A student, however, may opt not to put his or her quiz into this box and may instead hold onto the quiz until the second phase, which begins when students are told they can now open their notes, their textbooks, and talk with their neighbors about the possible answer. After another one minute period they place the quiz into a second box, which means they get, say, 20 points for a right answer and 15 points for a wrong answer. Students soon to catch onto the best strategy, which is to wait for the second round if they’re not sure of the answer.

The Importance of Fairness in ExamsThere should be no big surprises on an exam. Students should know what to expect, which is coverage of course topics, with question difficulty that finds your top students getting perfect or near-perfect scores. Your fairness as an instructor is judged by the fairness of your exams. Exams that cover what students expect are fair. Exams wherein top students excel also display your sense of fairness. How discouraging for students when class averages are so low that your not being on target moves you to play God at semester’s end and grade on the curve. Please read Paul Hewitt’s history of teaching and how he handled exams to lure more than a thousand students to his non-required conceptual physics course at City College of San Francisco in the October 2011 issue of The Physics Teacher.

Collaborative ExamsFor a significant learning experience, an exam may be offered in three phases: individual, team, and class. In the first phase each student takes the exam individually while also filling out a duplicate exam (or Scantron) that contains their answers but not their name. Assessment for this individual effort should be weighted the greatest. For example, each question may be worth 5 points, while for the second phase each question is worth 3 points, and for the third phase just 1 point.

A ten-minute warning is given to assure that all students finish with the first phase at about the same time. Exams are turned in while the duplicate student answers are spread out onto a broad table. Students then congregate into their teams to take the exam again, but this time working together and with resources, such as the textbook. They are also permitted to send a scout to inspect the duplicates to see how the rest of the class answered specific questions. Each member of the team should have a copy of the exam, but only one exam is to be turned in for assessment. Meanwhile, the instructor and/or TA is quickly grading the individual exams. (Use a Scantron if available.) The goal is to post the class average before the teams finish their team exams. This feedback allows teams to

gauge the value of the displayed duplicates. A quick alternative to grading all the exams is to post the average score of five random individual exams.

After teams turn in their team exams they are ready for the third phase in which they take the exam yet again together as a class. The instructor records their answers on a single master copy of the exam. Teams vote for an answer by holding up color-coded flash cards. Teams are allowed to argue their answers, but majority wins. If there is a tie among teams, then there is a recount after some healthy debate. After each class answer is recorded students are then told the correct answer, which is often followed by cheers or groans.

The length of the exam is determined by the duration of the class. For a 75-minute class, the exam can contain up to 25 questions. For 50-minute class, the exam should be narrowed down to about 15 questions. Timing is an important factor. In particular, students should finish the first phase all at about the same time. Slower students can be encouraged to come to class early for a head start. It is also helpful to have a second room where slower students can go in the event they need another 5 or 10 minutes to finish the first phase while their team move ahead. For the second phase, which is the team phase, it helps to include a “toughie” bonus short-essay question at the end of the exam. This is useful for teams who finish early—it keeps them busy while other teams are still working on the regular questions. There is not always sufficient time to have the third phase, which is when the class takes the exam together as a whole. To expedite the third phase, the instructor lays out the team answers so he or she can see all the team answers at a glance. Instant credit is given to questions that are unanimously correct. This allows the instructor to move on to some of the more difficult questions, which tend to have different answers from different teams.

By the time the class period is over, students have taken the exam three times and know their final score. Individual effort is preferentially rewarded, yet students still get the valuable experience of working together as a team. Furthermore, with such a format, the instructor can include challenging questions that may foil many individuals but not many teams. The individual phase of the exam may average 65 percent or less. This is

balanced, however, by the team and class phases, which may run 80 percent and 95 percent, respectively, so that the overall average is within the mid-70’s. One drawback to this format is that it consumes a lot of paper. If each student has access to a computer, however, the paper can be replaced by online delivery, which would also assist with the instant grading that makes this activity so effective.

AppealsWith end-of-semester course evaluations, a number one concern shown by most students is whether or not the course was fair. Toward satisfying this need, students may be permitted to appeal any question for which they believe they deserve credit. The instructor sets up the conditions of the appeal. For example, the student’s explanation for why they think they deserve credit must be hand-written and submitted within a certain time frame. Also, only those who were actively involved in the appeal, as indicated by their signature, have the possibility of gaining points. Appeals are reviewed by the instructor in the safety of his or her home or office where he/she may assign full, partial or no credit. Aside from providing students a sense of fairness on your part, the appeals provide the feedback you need to modify questions that might not be worded optimally. We should underscore that students really appreciate the opportunity to appeal, as will become evident on your course evaluations.

Student-Centered Learning Activities(What students can do when the instructor is not lecturing)

Team FormationsCollaborative learning tends to work best when students are grouped together in teams consisting of either 3 or 4 students. For a team of 5 students, invariably, the fifth student takes a back seat and is less involved. For a team of 2 students, there is not a sufficient diversity of ideas. Who goes on what team is the difficult responsibility of the instructor who knows that each team needs to be well-balanced in terms of academic abilities and gender. At the start of the semester, the instructor can eye-ball who goes where. Putting friends initially together is a good thing. Alternatively, the instructor can await the results of a Concepts Inventory and use student scores as the basis for team formations.

The instructor should consider new team formations after each exam. Students thus work together in the same team on up to the next exam, which is collaborative as described earlier. Exam scores are then used as the basis for new team formations.

The first assignment of any team is to agree upon a team name. The periodic table provides a wealth of possibilities. Team Titanium, Team Gold, and Team Einsteinium are some of the more popular choices.

Hands-On ScienceWithin each chapter of Conceptual Integrated Science are home-project type activities. These brief activities are most conducive to team learning in the classroom. As you can imagine, students appreciate the hands-on exploratory nature of these activities—they really help to liven up a class. The drawback is the time it takes to make sure that each team is set up with the proper materials, and to make sure that students clean up after themselves. We need not restrict all lab activities to the lab when there are so many small, safe, easy-to-set- up activities that can also be done effectively in class.

An important ancillary is Suzanne Lyons book, “Minds On Hands On,” loaded with intriguing activities and more. This ancillary is especially important to the instructor new to teaching the wide swath of Conceptual

Integrated Science.

Practice PagesAn important supplement to Conceptual Integrated Science are the Practice Pages, which are a set of minds-on concept review worksheets. The Practice Pages are designed as a study aid that students can work on outside of class. They are far more effective, however, when students work on them together as a team under the expert supervision of the course instructor, who travels from team to team to assist students as necessary. It is common that a Practice Page will prompt a question from a student that, in turn, prompts the instructor to give a short lecture presentation to the team. In such instances, neighboring teams can be encouraged to eavesdrop. This is known as “targeted teaching” and it arises as the instructor roams about the room checking on team progress. Occasionally, it prompts the instructor to switch gears and give his or her mini-presentation to the whole class. Targeted teaching is impromptu and in response to immediate student need.

Think-Pair-ShareThis technique was made popular by Eric Mazur of Harvard University in his book Peer Instruction: A User’s Manual. A multiple-choice question is presented to the class. Students contemplate the question on their own and then commit to an answer preferably in writing or via flash cards so that the instructor can quickly gauge student performance. Students then discuss their reasoning with neighboring students. After student–student discussions, a second survey of answers is taken. If the responses prove satisfactory, the instructor can move on to the next concept. If students are struggling, then the instructor may decide to spend more time clearing up misconceptions.

Readiness Assurance Test (RAT)Hands down, this is the student’s favorite activity—not for the joy of it but because it is most related to helping him or her perform well on exams. The RAT is simply a trial exam given before the actual exam. It helps students assess how ready they may or may not be for the exam. Everything about the

RAT should be identical to the exam except that the points don’t count and the questions are different!

You will find that there are short RATs already given at the end of each chapter. You might consider building your RAT using these questions. Alternatively, if you formulate your own RAT questions, you might consider using some of the textbook’s RAT questions for your exam to reward students who have been working with the questions at the back of each chapter.

But in implementing a RAT you will come across a deep question, which is “Should you offer a RAT during a class before an exam when this means losing a day of instruction?” If you use the “collaborative exams” technique described earlier, then you will quickly come to find that you are by no means “losing a day of instruction” when you implement a RAT. Rather, you are helping your students to solidify their understanding of science, which may be an important aspect of your job description. Does implementing a RAT mean you will need to cut back on topics normally covered in your syllabus? Not necessarily. Some students actually learn well by reading the textbook. Others prefer watching the textbook authors deliver their “talking textbook” video lessons at ConceptualAcademy.com (Please check us out!). All students will appreciate solidifying their understanding of these topics (such as rainbows, nuclear physics, natural selection, the rock cycle or the solar system) in class under your expert guidance. The RAT is a good vehicle for this purpose.

Class Presentations with Activity IntervalsSelect questions are assigned to teams of students who then have a short period of time (10 minutes) to prepare and practice articulating an answer. Students as individuals or as a team then get up in front of the class to articulate their answers in a short two-minute presentation. They then ask the class if there are any questions. The instructor, meanwhile, has planted some well-thought-out questions among the audience who then ask these questions, which probe deeper into the concepts. The presenting student or students can either respond or choose to serve as moderators of a class discussion.

Certain questions lend themselves to short but effective hands-on activities. After a student presentation on surface tension, for example, the class can be

challenged to float a paperclip on water. Or after a presentation on condensation, the instructor can invert a steam-filled soda can in water. Students are then prompted to explain why the can imploded. Of course, if they can’t figure it out, it is the responsibility of the instructor to keep quiet or provide only hints.

Questions that work well for this technique include the Think and Explain questions from the textbook. These questions also lend themselves well to study group sessions either outside of class or during class. A student should be reminded that if he or she understands the answer to one of these questions—if he or she really does—then he or she should be able to articulate the answer (verbally!) to someone else, such as a fellow student. Note: Isn’t this remindful of when we learned most about a subject: when we articulated it to others?

Focused ListingOn a blank sheet of paper, students write down a list of 4 or 5 terms or phrases that summarize the content of a textbook section or reading assignment. This activity quickly assesses what key concepts were difficult for the student to understand. A related activity described by Angelo and Cross is called “The Muddiest Point” whereby students write down concepts from a chapter that were most unclear. The instructor then uses this information to launch a class presentation (mini-lecture or demonstration) or a class discussion à la the Socratic method whereby everything the instructor says is phrased as a question.

Reward RaceA set of not-so-easy multiple choice questions are posted around the room. Students work in teams to answer these questions. The first team to get all answers correct wins the prize, preferably something made of chocolate. Strategies are important. Some teams will decide to split up. Others will stay huddled as they migrate from one question to the next. Also, if a team submits answers but gets at least one wrong, they are not allowed to submit answers again until either all the other teams have had a chance or after a specified amount of time. Furthermore, the instructor does not tell teams which

questions they got wrong, only the number of them they got wrong. This is certainly one of the more fun activities.

Office VisitsWhile the class is occupied with some learning activity (pensive activities, such as the Practice Sheets are best), the instructor pulls individual students away for a required brief office visit. The instructor inquires about how things are going and whether the student has any general or specific questions or concerns. This is also a good time to show the student his or her present course grade and provide advice on how to do well in the course. Furthermore, this activity serves as an important ice-breaker that makes students more inclined to visit you outside of class.

Field Trip Class-size permitting, take students on a tour of any science research laboratories near you. Ask your colleagues and University researchers whether they would be willing to talk to your students about why they like science and why they chose it as a profession.

The Conceptual CaféBring in a stack of recent science journals, both popular and technical, and set the classroom up as though it were a coffee house—quiet background music, tea, donuts, etc. Students merely spend the class time reading through these journals and discussing science-related topics with their peers as well as the instructor. Few, if any, students will likely have looked through a rigorous technical journal, such as the Journal of the American Chemical Society. These journals can be intimidating for their detail, especially the experimental sections. But students should have some first hand experience at the utterly vast amount of information that has been generated and is being generated by scientists around the world. After looking at the technical journals, students will find the popular science magazines to be a breath of fresh air. It’s likely that most of your students have never read through a popular science magazine. Perhaps, down the road this activity will help them to think twice

about throwing away one of those pervasive science magazine subscription offers.

Instructor-Centered Learning Activities(What the instructor can do outside of class)

Class JournalStudent-centered learning is such fertile ground for educational innovation. As soon as possible after class, we encourage you to open up your Class Journal and start recording what went well and what went wrong. We can almost guarantee that through this process ideas for improvements will arise. The process of writing in your journal, especially soon after class, is a great way to allow these ideas to come to the surface where you can consider them in fuller detail.

Think-Pair-ShareTry Think-Pair-Share with your colleagues. First, think about your curriculum using your class journal. Discuss your experiences and ideas with your colleagues. Then share your ideas with others through departmental seminars or regional or national meetings. The key word here is synergy. We instructors don’t work in a vacuum. In working together we can fast-forward to better ways of reaching our non-science oriented students.

Explore ReferencesHere are a few references about student-centered learning techniques.

Thomas A. Angelo, K. Patricia Cross, Classroom Assessment Techniques, A Handbook for College Teachers, 2nd ed., Jossey-Bass, 1993.

Eric Mazur, Peer Instruction: A User’s Manual, Prentice-Hall, 1997.

Jeffrey P. Adams, Timothy F. Slater, Strategies for Astro 101, Prentice-Hall, 2003.

Chemical Concepts Inventoryhttp://jchemed.chem.wisc.edu/JCEDLib/QBank/collection/CQandChP/CQs/ConceptsInventory/CCIIntro.html

or just type: “Chemical Concepts Inventory” into Google.

Collaborative learning activitieswww.wcer.wisc.edu/nise/cl1/cl/

Field-Tested Assessment Guide (CATs)www.flaguide.org

Just in Time Teachingwww.JiTT.org

Process Oriented Guided Inquiry Learning (POGIL)www.POGIL.com

“The Missing Essential — A Conceptual Understanding of Physics” Paul Hewitt’s Millikan Award talk, American Journal of Physics, January 1983.

Some Teaching Tips • Attitude toward students and attitude about science in general is of utmost importance: Consider yourself not the master in your classroom, but the main resource person, the pacesetter, and the guide. Consider yourself a bridge between your student’s ignorance and some of the information you’ve acquired in your study. Guide their study—steer them away from the dead ends you encountered, and keep them on essentials and away from time-draining peripherals. You are there to help them. If they see you so, they’ll appreciate your efforts. This is a matter of self-interest. An appreciated teacher has an altogether richer teaching experience than an under-appreciated teacher.

• Don’t be a “know-it-all.“ When you don’t know your material, don’t pretend you do. You’ll lose more respect faking knowledge, than not having it. If you’re new to teaching, students will understand you’re still pulling it together, and will respect you nonetheless. But if you fake it, and they CAN tell, whatever respect you’ve earned plummets.

• Be firm, and expect good work of your students. But be fair and get papers graded and returned quickly. Be sure the bell curve of grades reflects a reasonable average. If you have excellent students, some should score 100% or near 100% on exams. This way you avoid the practice of fudging grades at the end of the term to compensate for off-the-mark low exam scores. The least respected professor in my memory was one who made exams so difficult that the class average was near the noise level, where the highest marks were some 50%.

• Be sure that what knowledge you want from your students is reflected by your test items. The student question, “Will that be on the test?“ is a good question. What is important—by definition—is what’s on the test. If you consider a topic important, allow your students credit for their feedback on that topic. An excellent student should be able to predict what will be on your test. Remember your own frustration in your student days of preparing for a topic only to find it not part of the test? Don’t let your students experience the same. Many short questions that fairly span course content is the way to go.

• Consider having students repeat work that you judge to be poor—before it gets a final grade. A note on a paper saying you’d rather not grade it until they’ve given it another try is the mark of a concerned and caring teacher.

• Do less professing and more questioning. Information that is of value ought to be the answer to a question. Having frequent “check-your-neighbor“ intervals should be an important feature of your class. Their feedback to you can be immediate with the use of student whiteboards, or their electronic counterparts. Beware of the pitfall of too quickly answering your own questions. Use “wait-time,“ where you allow ample time before giving the next hint.

• Show respect for your students. Although all your students are more ignorant of physics than you are, some are likely more intelligent than you are. Underestimating their intelligence is likely overestimating your own. Respect is a two-way street.

1 About Science

1.1 A Brief History of Advances in Science1.2 Mathematics and Conceptual Integrated Science

Math Connection: Equations as Guides to Thinking1.3 The Scientific Method—A Classic Tool1.4 The Scientific Hypothesis1.5 The Scientific Experiment1.6 Facts, Theories, and Laws

Science and Society: Pseudoscience1.7 Science Has Limitations1.8 Science, Art, and Religion1.9 Technology—The Practical Use of Science1.10 The Natural Sciences: Physics, Chemistry, Biology, Earth Science, and Astronomy1.11 Integrated Science

Integrated Science—Chemistry and Biology: An Investigation of Sea ButterfliesA common practice is spending the first week of a science class on the tools of science—unit conversions, significant figures, making measurements, and using scientific notation. This is anything but exciting to most students. The authors of this book believe that this is pedagogical folly. How much better it is if the first week acts as a hook to promote class interest, with tools introduced if and when they are needed later in the course. So, this book begins by introducing the nature of science, the value of integrated science, the scientific method, the role of science in society, and other topical issues such as pseuodoscience, the relationship between science and religion, and the similarities and differences among science and art.

Screen casts on the web, “Hewitt drew it”:

Although there’s no cast particularly for this chapter, Hewitt’s passion for physics is nicely treated in the first Screencast #1; The Equilibrium Rule.

In Next-Time Questions:• Hypotheses

In the Lab Manual:• Tuning the Senses (enhancing perception)• Making Cents (introduces the mass balance and the making of a simple graph)

Suggested PresentationA Brief History of Advances in Science

Science is organized knowledge. Its roots are found in every culture. The Chinese discovered printing, the compass, and rockets; Islamic cultures developed algebra and lenses; mathematicians in India developed the concept of zero and infinity. This text, nevertheless, emphasizes Western science. Science did advance faster in Western than in Eastern cultures, largely because of the different social and political climates.

While early Greeks, in an era of experimental democracy and free thinking, were questioning their speculations about the world, their counterparts in the more authoritarian eastern parts of the world were largely occupied in absorbing the knowledge of their forebears. In regions like China, absorbing this knowledge was the key to personal success. So scientific progress in Eastern cultures was without the early period of questioning that accelerated the scientific advances of Europe and Eurasia. In any event, it is important to emphasize throughout your course that all science is a human endeavor. In addition to being a legacy of what humans have learned about nature, it’s also a human activity that answers questions of human interest. It is done by and for humans.

You may consider elaborating the idea that the test of correctness in science is experiment. As Einstein once said, “many experiments may show that I’m right, but it takes only one experiment (that can be repeated) to show that I’m wrong.” Ideas must be verifiable by other scientists. In this way science tends to be self-correcting.

Mathematics and Conceptual Integrated ScienceThe mathematical structure of science is evident in this book by the many equations. These are shorthand notations of the connections and relationships of nature. They are seen primarily as guides to thinking, and only secondarily as recipes for solving problems. Many instructors bemoan students who reach for a formula when asked a scientific question. We authors take a more positive view of this, for formulas are shorthand statements about the connections of concepts. For example, if asked if speed affects the force of gravity on earth satellites, a look at the equation for gravitation tells us no—only mass and distance affect force. Now if speed changes the distance, then in that case, yes. When equations are seen as guides to thinking, then conceptual thinking is present. Hooray!

You can provide a specific example of “equations as guides to thinking” by going over the Math Connection box. This feature is meant to clarify the role of math in Conceptual Integrated Science rather than to challenge students. The notions of direct and inverse proportions are intuitively easy to grasp—showing that science often has a mathematical structure, but this structure need not be difficult to grasp.

The Scientific Method—A Classic ToolThe scientific method is given in a six-step form. We say that science is structured common sense. The scientific method is an example. The scientific method is to be seen as a sensible way to go about investigating nature. Although the six steps are useful, they don’t merit your students memorizing them. And most often, they are not the specific steps used in scientific discoveries. The scientific attitude, more than a particular method, underlies scientific discovery.

A Scientific Attitude Underlies Good Science  Expand on the idea that honesty in science is not only a matter of public interest but is also a matter of self-interest. Any scientist who misrepresents or fudges data, or is caught lying about scientific information, is ostracized by the scientific community. There are no second chances. The high standards for acceptable

performance in science, unfortunately, do not extend to other fields that are as important to the human condition. For example, consider the standards of performance required of politicians.

Scientific HypothesesDistinguish between hypothesis, theory, fact, and concept. Point out that theory and hypothesis are not the same. A theory applies to a synthesis of a large body of information. The criterion of a theory is not whether it is true or untrue, but rather whether it is useful or not. It is useful even though the ultimate causes of the phenomena it encompasses are unknown. For example, we accept the theory of gravitation as a useful synthesis of available knowledge that relates to the mutual attraction of bodies. The theory can be refined, or with new information, it can take on a new direction. It is important to acknowledge the common misunderstanding of what a scientific theory is, as revealed by those who say, “But it is not a fact; it is only a theory.” Many people have the mistaken notion that a theory is tentative or speculative, while a fact is absolute.

Impress upon your class that a fact is not immutable and absolute, but it is generally a close agreement by competent observers of a series of observations of the same phenomena. The observations must be verifiable. Because the activity of science is the determination of the most probable, there are no absolutes. Facts that were held to be absolute in the past are seen altogether differently in the light of present-day knowledge and observational equipment.

By concept, we mean an intellectual framework that is part of a theory. We speak of the concept of time, the concept of energy, or the concept of a force field. Time is related to motion in space and is the substance of the Theory of Special Relativity. We find that energy exists in tiny grains, or quanta, which is a central concept in the Quantum Theory. An important concept in Newton’s Theory of Universal Gravitation is the idea of a force field that surrounds a material body. A concept is an idea with various applications. Thus, when we think “conceptually,” we use a generalized way of looking at things.

Prediction in science is different from prediction in other areas. In the everyday sense, one speaks of predicting what has not yet occurred, like whether or not it will rain next weekend. In science, however, prediction is not so much about what will happen, but about what is happening and is not yet noticed, like what the properties of a hypothetical particle are or are not. A scientist predicts what can and cannot happen, rather than what will or will not happen.

Science Has LimitationsJust as a great strength of a democracy is its openness to criticism, likewise with science. This is in sharp contrast to dogma, which is seen as absolute. The limitations of science, like those of democracy, are open for improvement. The world has suffered enormously from those who have felt their views were beyond question. Author K. C. Cole says it well when she asserts that belief in only one truth and being the possessor of it is the deepest root of all the evil that is in the world.

PseudoscienceThe material on pseudoscience should be excellent for student discussions. A stimulating exercise is to ask students to formulate a series of questions that help determine whether a given claim is a case of pseudoscience. Such a list might include the following questions, and more:• Does the claim use technical-sounding jargon that is not precisely defined?• Does the claim use scientific words imprecisely and in a nonscientific context (e.g., “energy,” “frequency,” “vibration”)?

• Do proponents complain of being overly criticized?• Is one reason given for the supposed validity of the claim that it has been around a long time (so it must be true)?• Do proponents of the claim use the logical fallacy of the ad hominum to respond to critics? (An ad hominem argument is a challenge directed at he who expresses an idea rather than at the idea itself.)

Pseudoscience is very big business, and examples of it abound. Help students understand the difference between nonscience, science, pseudoscience, and protoscience (a new science trying to establish legitimacy).

The Search for Order—Science, Art, and ReligionEinstein said, “Science without religion is deaf; religion without science is blind.” The topic of religion in a science text is rare. We treat it briefly only to address what is foremost on many students’ minds. Do religion and science contradict each other? Must one choose between them? We hope our very brief treatment presents a satisfactory answer to these questions. Our take is that religion and science are compatible when they address different realms. When the certainty often associated with particular religions spills over into science, then there is an unfortunate incompatibility between religion and science.

Technology—Practical Use of the Findings of ScienceIn discussions of science and technology and their side effects, a useful statement is: You can never do just one thing. Doing this affects that. Or, You can never change only one thing. Every time you show an equation, it’s evident that changing a variable on one side of the equation changes one or more on the other side. This idea is nicely extended with “there is never just one force” in discussions of Newton’s third law.

The Natural Sciences: Physics, Chemistry, Biology, Earth Science, and AstronomyWith regard to science courses and liberal arts courses, there is a central factor that makes it difficult for liberal arts students to delve into science courses the way that science students can delve into liberal arts courses—and that’s the vertical nature of science courses. They build upon each other, as noted by their prerequisites. A science student can take an intermediate course in literature, poetry, or history at any time. But in no way can a humanities student take an intermediate physics or chemistry course without first having a foundation in elementary physics and mathematics. Hence the importance of this conceptual course.

Integrated ScienceComing into this course, students may be hazy about what integrated science is. Yet, once you explain it to them, they will readily grasp the value of it. When asked “Why study integrated science?” one student simply stated “Because life is integrated.” We fully agree. Point out to students that they will see over and over in this text—and in their everyday lives—that the branches of science are interconnected. How can one understand the host of interesting and important scientific phenomena—from global warming to the origin of the solar system to forensic medicine—without integrating concepts from different branches of science?

An Investigation of Sea Butterflies  This case study examines the scientific method as actually applied as well as provides a specific example of integrated science. Another important point discussed is the idea of a scientific control—a basic feature of a valid scientific experiment. This idea can be rather subtle, so you may want to emphasize it in your lecture. Consider using the concept check questions for this feature as check-your-neighbor questions—they get at the main ideas of this section.

2 Describing Motion

2.1 Aristotle on Motion2.2 Galileo’s Concept of Inertia

History of Science: AristotleHistory of Science: Galileo

2.3 Mass—A Measure of Inertia2.4 Net Force2.5 The Equilibrium Rule

Science and Society: Paul Hewitt and the Origin of Conceptual Integrated Science2.6 The Support Force

Math Connection: Applying the Equilibrium Rule2.7 Equilibrium of Moving Things2.8 The Force of Friction

Integrated Science—Biology, Astronomy, Chemistry, and Earth Science: Friction Is

Universal2.9 Speed and Velocity2.10 Acceleration

Integrated Science—Biology: Hang Time

Demonstration EquipmentCoat hanger and clay blobsWooden block stapled to a piece of cloth (to simulate tablecloth pull)Tablecloth (without a hem) and a few dishes (for the tablecloth pull)Piece of rope for a classroom tug-of-warWooden cube that will fit on a pan balance (another material such as cardboard will do)Pan balance

This chapter introduces students to kinematics and dynamics. Kinematics is the study of motion without regard to the forces that produce it. When forces are considered, the study is then of dynamics. The authors believe that one of the great follies of physics instruction is overtime on kinematics. Whereas many physics books begin with a chapter on kinematics, this is downplayed in this book. We treat only the amount of kinematics needed, mainly distinguishing between velocity and acceleration as a launching to Newton’s laws that follow. Please do not focus undue attention on the kinematics concepts of speed and the “puzzels” that better belong in a math class. And please spare your students graphical analysis of these topics, which is better left to a math class or a follow-up physics course. Mastering motion graphs is more of an uphill task than

getting a grip on the concepts themselves (but try telling that to a teacher who has a passion for graphical analysis!) Too-early emphasis on kinematics can bog a course down at the outset. So, lightly treat the sections on speed, velocity, and acceleration. Develop the concept of net force, then move as smoothly as you can to where the meat is—the next chapter on Newton’s laws of motion.

Of particular interest to me (Hewitt) is the Personal Essay in the chapter, which relates to events that inspired me to pursue a life in physics—my meeting with Burl Grey on the sign-painting stages of Miami, Florida. Relative tensions in supporting cables is what first caught my interest in physics, and I hope to instill the same interest in your students with this chapter. My first screencast (look under “Hewit drew it” on the web) tells the story of my meeting Burl, and how I was inspired to study physics.

So force, rather than kinematics, is the emphasis of this chapter. And force vectors, only parallel ones at this point, are the easiest to understand. They underlie the equilibrium rule: F = 0 for systems in equilibrium. These are further developed in the Practice Book. (Not using the Practice Book is like teaching swimming away from water. This is an important book—the authors’ most imaginative and pedagogically useful tool for student learning!)

Note that in introducing force, we first use pounds—most familiar to your students. A quick transition, without fanfare, introduces the newton. We don’t make units a big deal and don’t get into the laborious task of unit conversions, which is more appropriate for physics majors.

A brief treatment of units and systems of measurement is provided in Appendix A.

If you get deeply into motion, you can consider the Sonic Ranger lab, which uses a sonar ranging device to plot in real time the motion of students, rolling balls, or whatever. This lab can be intriguing, so be careful that it doesn’t swallow too much time. Again, overtime on kinematics is the black hole of physics teaching!

Screen casts on the web, “Hewitt drew it”:• 1. The Equilibrium Rule• 2. Equilibrium Problems• 3. Net Force and Vectors• 4. Nellie’s Rope Tensions• 5. Nellie’s Ropes• 7. Force Vectors on an Incline• 8. Linear Motion Definitions• 9. Bikes and Bee Problem• 10. Unit Conversion• 11. Velocity Vectors• 12. Free Fall• 18. Acceleration Units

In the Practice Book:• Vectors and Equilibrium• Free Fall Speed• Acceleration of Free Fall

In Next-Time Questions:• The Scaffold in Equilibrium

• The Bee and the Bicycle

In the Lab Manual:• Go Go Go! (experiment on graphing motion)• Sonic Ranger (activity on graphing motion)• Walking the Plank (activity)

Suggested PresentationBegin by holding up the textbook and remarking on its vast amount of information. A look at the table of contents shows there is much to cover. Whereas some material will be covered in depth, some will not. State that they will come to feel quite comfortable with an understanding of much of the content, but not all. There isn’t time for a thorough treatment of all material. So rather than bogging down at the beginning of your course and ending up racing over material at the term’s end, you’re going to do it the other way around, and race through this beginning chapter. Rather than tilling this soil with a deep plow setting, you’re going to skim it and dig in later. (This will help you avoid overtime on kinematics!)

Your first question: What means of motion has done more to change the way cities are built than any other? [Answer: The elevator!]

Explain the importance of simplifying. Explain that motion, for example, is best understood by first neglecting the effects of air resistance, buoyancy, spin, and the shape of the moving object. Beneath these factors are simple relationships that may otherwise be masked. So you’ll concentrate on simple cases and avoid complexities. State that you’re not trying to challenge them, but to teach them some of the physical science that you yourself have learned. Better they understand a simple case than be miffed by a complicated one that less clearly focuses on the main concept being treated.

Aristotle’s Classification of MotionBriefly discuss Aristotle’s views on motion. His views were a good beginning for his time. They were flawed from the point of view of what we know today, but his efforts to classify all things, motion being one of them, was a boost in human thinking. Perhaps we remember him too much for his errors, when in total, he did much to shape good thinking in his time.

Galileo’s Concept of InertiaAcknowledge the chief difference between Aristotle’s approach and that of Galileo. The big difference between these two giant intellects was the role of experiment—emphasized by Galileo. The legendary experiment at the Leaning Tower of Pisa is a good example. Interestingly, legend has it that many people who saw the falling objects fall together continued to teach otherwise. Seeing is not always believing. Ideas that are firmly established in one’s thinking are difficult to change. People in science must be prepared to have their thinking challenged often.

Point to an object in the room and state that if it started moving, one would reasonably look for a cause for its motion. We would say that a force of some kind was responsible, and that would seem reasonable. By force, you mean quite simply, a push or a pull. Tie this idea to the notion of force maintaining motion as Aristotle saw it. State that a cannonball remains at rest in the cannon until a force is applied, and that the force of expanding gases drives the ball out of the barrel when it is fired. But what keeps the cannonball moving when the gases no longer act on it?

Galileo wondered about the same question when a ball gained speed in rolling down an incline but moved at constant speed on a level surface. This leads you into a discussion of inertia. In the everyday sense, inertia refers to a habit or a rut. In physics, it’s another word for laziness, or the resistance to change as far as the state of motion of an object is concerned. Inertia was first introduced not by Newton, but by Galileo as a result of his inclined-plane experiments. You’ll return to this concept when Newton’s first law is treated in the following chapter.

How much inertia an object has is related to the amount of mass the object has. Mass is a measure of the amount of material in an object. Weight is the gravitational attraction of the earth for this amount of material. Whereas mass is basic, weight depends on location. You’d weigh a lot more on Jupiter than on Earth, and a lot less on the surface of the moon. Mass and weight are proportional; hence, they are often confused.

Mass is sometimes confused with volume. Comparing an overstuffed fluffy pillow to a small automobile battery should convince anyone that mass and volume are different. The unit of mass is the kilogram, and the unit of volume is cubic meters or liters.

Density is a concept of fundamental importance and is often confused with both mass and volume. Try the following demo to make the concept of density clear. Measure the dimensions of a large wooden cube in centimeters, and find its mass with a pan balance. Define density = mass/volume. (Use the same cube when you discuss flotation later.) Some of your students will unfortunately conceptualize density as massiveness or bulkiness rather than massiveness per bulkiness, even when they give a verbal definition properly. This can be helped with the following:

CHECK YOUR NEIGHBOR: Which has the greater density, a cupful of water or a lake-full of water? A kilogram of lead or a kilogram of feathers? A single uranium atom or the world?

I jokingly relate breaking a candy bar in two and giving the smaller piece to my friend who looks disturbed. “I gave you the same density of candy bar as I have.”

Contrast the density of matter and the density of atomic nuclei that comprise so tiny a fraction of space within matter. From about 2 g/cm3 to 2 1014 g/cm3. And in a further crushed state, the interior of neutron stars, about 1016 gm/cm3.

Mass Versus WeightTo distinguish between mass and weight, compare the efforts of pushing horizontally on a block of slippery ice on a frozen pond versus lifting it. Or consider the weightlessness of a massive anvil in outer space and how it would be difficult to shake. And if it were moving toward you, it would be harmful to be in its way because of its great tendency to remain in motion. The following demo (often used to illustrate impulse and momentum) makes the distinction nicely:

DEMONSTRATION: Hang a massive ball by a string and show that the top string breaks when the bottom is pulled with gradually more force, but the bottom string breaks when the string is jerked. Ask which of these cases illustrates weight. (Interestingly enough, it’s the weight of the ball that makes for the greater tension in the top string.) Then ask which of these cases illustrates inertia. (When jerked, the tendency of the ball to resist the sudden downward acceleration, its inertia, is responsible for the lower string breaking.) This is the best demo we know of for showing the different effects of weight and mass.

One Kilogram Weighs 10 Newtons

Suspend a 1-kg mass from a spring scale and show that it weighs 9.8 N. We round this off to 10 N, for precision is not needed at this stage of learning.

Units of Force—NewtonsI suggest not making a big deal about the unfamiliar unit of force—the newton. I simply state that it is the unit of force used by physicists, and if students find themselves uncomfortable with it, simply think of “pounds” in its place. Relative magnitudes, rather than actual magnitudes, are the emphasis of conceptual integrated science anyway. Do as my inspirational friend Burl Grey does in Figure 2.10 and suspend a familiar mass from a spring scale. If the mass is a kilogram and the scale is calibrated in newtons, it will read 9.8 N. If the scale is calibrated in pounds, it will read 2.2 pounds. State that you’re not going to waste valued time in unit conversions. (Students can do enough of that in one of those dull physics courses they’ve heard about.) [I do a short lesson on Unit Conversion in Screencast #10 that will save you classtime.]

CHECK YOUR NEIGHBOR: Which has more mass, a 1-kg stone or a 1-lb stone? [A 1-kg stone has more mass, for it weighs 2.2 lb. But we’re not going to make a fuss about such conversions. If the unit newton bugs you, think of it as a unit of force or weight in a foreign language for now!]

Net ForceDiscuss the idea of more than one force acting on something, and the resulting net force. Figure 2.9 captures the essence. Here’s where you can introduce vectors. Note that the forces in the figure are represented by arrows. Drawn to scale, these are vectors. Briefly distinguish between vector quantities (like force, velocity, and, as we shall see, acceleration) and scalar quantities (time, mass, volume).[Screencast #3 on Net Force is also a time saver.]

Equilibrium for Objects at RestCite other static examples, where the net force is zero as evidenced by no changes in motion. Hold the 1-kg mass at rest in your hand and ask how much net force acts on it. Be sure they distinguish between the 9.8 N gravitational force on the object and the zero net force on it—as evidenced by its state of rest. (The concept of acceleration is introduced shortly.) When suspended by the spring scale, point out that the scale is pulling up on the object, with just as much force as the earth pulls down on it. Pretend to step on a bathroom scale. Ask how much gravity is pulling on you. This is evident by the scale reading. Then ask what the net force is that acts on you. This is evident by your absence of any motion change. Consider two scales, one foot on each, and ask how each scale would read. Then ask how the scales would read if you shifted your weight more on one scale than the other. Ask if there is a rule to guide the answers to these questions. There is:F = 0 For any object in equilibrium, the net force on it must be zero. Before answering, consider the skit outlined below.

Sign Painter Skit  Draw on the board the sketch below, which shows two painters on a painting rig suspended by two ropes. [Again, Screencast #1 covers this.]

Step 1: If both painters have the same weight and each stands next to a rope, the supporting force in the ropes will be equal. If spring scales were used, one on each rope, the forces in the ropes would be evident. Ask what the scale readings in each rope would be in this case. [The answer is that each rope will support the weight of one man + half the weight of the rig—both scales will show equal readings.]

Step 2: Suppose one painter walks toward the other as shown in the sketch, which you draw on the chalkboard (or show via overhead projector). Will the reading in the left rope increase? Will the reading in the right rope decrease? Grand question: Will the reading in the left rope increase exactly as much as the decrease in tension in the right rope? And if so, how does either rope “know” about the change in the other rope? After neighbor discussion, be sure to emphasize that the answers to these questions lie in the framework of the Equilibrium Rule: F = 0. Because there is no change in motion, the net force must be zero, which means the upward support forces supplied by the ropes must add up to the downward force of gravity on the two men and the rig. So a decrease in one rope must necessarily be met with a corresponding increase in the other. (This example is dear to my heart. Both Burl and I didn’t know the answer way back then—because neither he nor I had a model for analyzing the problem. We didn’t know about Newton’s first law and the Equilibrium Rule. How different one’s thinking is depends on whether there is a model or guidance. If Burl and I had been mystical in our thinking, we might have been more concerned with how each rope “knows” about the condition of the other. This is the approach that intrigues many people with a nonscientific view of the world.)

The Support Force (Normal Force)Ask what forces act on a book at rest on your lecture table. Then discuss Figure 2.12, explaining that the atoms in the table behave like tiny springs. This upward support force is equal and opposite to the weight of the book, as evidenced by the book’s state of rest. The support force is a very real force. Because it is always perpendicular to the surface, it is called a normal force. Without it, the book would be in a state of free fall.

Friction—A Force That Affects MotionDrag a block at constant velocity across your lecture table. Acknowledge the force of friction, and how it must exactly counter your pulling force. Show the pulling force with a spring balance. Now, because the block moves without accelerating, ask for the magnitude of the friction force. It must be equal and opposite to your scale reading. Then the net force is zero. While sliding, the block is in dynamic equilibrium. That is, F = 0.

Equilibrium of Moving ThingsIf you’re in the car of a smoothly moving train and you balance a deck of cards on a table, they are in equilibrium whether the train is in motion or not. If there is no change in motion (acceleration), the cards don’t “know the difference.”

Speed and VelocityDefine speed, writing its equation in longhand form on the board while giving examples (automobile speedometers, etc.). Similarly define velocity, citing how a race car driver is interested in his speed, whereas an airplane pilot is interested in her velocity (speed and direction). [More than enough information on kinematic definitions is in Screencast #8.]

Motion Is RelativeAcknowledge that motion is relative to a frame of reference. When walking down the aisle of a train at 1 m/s, your speed relative to the floor of the train is different than your speed relative to the ground. If the train is moving at 50 m/s, then your speed relative to the ground is 51 m/s if you’re walking forward, or 49 m/s if you’re walking toward the rear of the train. Tell your class that you’re not going to make a big deal about distinguishing between speed and velocity, but

you are going to make a big deal of distinguishing between speed or velocity and another concept—acceleration.

Galileo and AccelerationDefine acceleration, identifying it as a vector quantity, and cite the importance of change. That’s change in speed, or change in direction. Hence, both are acknowledged by defining acceleration as a rate of change in velocity rather than speed. Ask your students to identify the three controls in an automobile that enable the auto to change its state of motion—that produce acceleration (accelerator, brakes, and steering wheel). State how one lurches in a vehicle that is undergoing acceleration, especially for circular motion, and state why the definition of velocity includes direction to make the definition of acceleration all-encompassing. Talk of how without lurching one cannot sense motion, giving examples of coin flipping in a high-speed aircraft versus doing the same when the same aircraft is at rest on the runway.

Units for AccelerationGive numerical examples of acceleration in units of kilometers/hour per second to establish the idea of acceleration. Be sure that your students are working on the examples with you. For example, ask them to find the acceleration of a car that goes from rest to 100 km/h in 10 seconds. It is important that you not use examples involving seconds twice until they taste success with the easier kilometers/hour per second examples. Have them check their work with their neighbors as you go along. Only after they get the hang of it, introduce meters/second/second in your examples to develop a sense for the units m/s2. [Screencast #18 covers this].

Falling ObjectsCHECK YOUR NEIGHBOR: If an object is dropped from an initial position of rest from the top of a cliff, how fast will it be traveling at the end of 1 second? (You might add, “Write the answer on your notepaper.” And then, “Look at your neighbor’s paper—if your neighbor doesn’t have the right answer, reach over and help him or her—talk about it.”)

After explaining the answer when class discussion dies down, repeat the process, asking for the speed at the end of 2 seconds, and then for 10 seconds. This leads you into stating the relationship v = gt, which by now you can express in shorthand notation. After any questions, discussion, and examples, state that you are going to pose a different question—not asking for how fast, but for how far. Ask how far the object falls in 1 second.

Ask for a written response and then ask if the students could explain to their neighbors why the distance is only 5 m rather than 10 m. After they’ve discussed this for almost a minute or so, ask, “If you maintain a speed of 60 km/h for 1 hour, how far do you go?”—then, “If you maintain a speed of 10 m/s for 1 second, how far do you go?” Important point: You’ll appreciably improve your instruction if you allow some thinking time after you ask a question. Not doing so is the folly of too many teachers. Then continue, “Then why is the answer to the first question not 10 meters?” After a suitable time, stress the idea of average velocity and the relation d = vt. [Screencast #12 treats Free Fall.]

For accelerating objects that start from a rest position, the average velocity is half the final velocity (average velocity = [initial velocity + final velocity]/2).

CHECK YOUR NEIGHBOR: How far will a freely falling object that is released from rest fall in 2 seconds? In 10 seconds? (When your class is comfortable with this, then ask how far in 1/2 second.)

Investigate Figure 2.23 and have students complete the speed readings. Ask what odometer readings (that measure distance) would be for the speeds shown. To avoid information overload, we restrict all numerical examples of free fall to cases that begin at rest. Why? Because it’s simpler that way. (We prefer our students understand simple physics rather than be confused about not-so-simple physics!) We do go this far with them:

Two-Track DemoLook ahead at the two tracks shown in Exercise 79. With your hand, hold both balls at the top end of the tracks and ask which will get to the end first. Or you can quip, which will win the race, the slow one or the fast one? Or, the one with the greatest average speed or the one with the smaller average speed? Asked these latter ways, the question guides the answer. But be ready to find that most students will intuitively know the balls will reach the end with the same speed. (This is more obvious from a conservation of momentum point of view.) But the question is not of speed, but of time—which gets there first. And that’s a challenge to realize that! The speed gained by the ball on the lower part of the dipped track is lost coming up the other side, so, yes, they reach the end with the same speed. But the gained speed at the bottom of the dip means more average speed overall. You’ll get a lot of discussion on this one. You can make your own tracks quite simply. I got this idea from my friend and colleague, Chelcie Liu, who simply bought a pair of equal length bookcase supports and bent them by hand. They are more easily bent with the aid of a vice. [These tracks make a concluding question in Screencast #31, when the conservation of energy is discussed.]

Integrated Science—Biology, Astronomy, Chemistry, and Earth Science: Friction Is UniversalTo make the point that friction is indeed universal, break students into small groups and ask them to list examples of friction that relate to each of the major science subject areas—physics, chemistry, biology, earth science, and astronomy. Have students state their examples so all can appreciate the diversity of friction applications. Also, you might have a brick available to students interested in verifying the concept discussed in the Concept Check question for themselves.

Integrated Science—Biology: Hang TimeThis fascinating idea completes the chapter. Most students (and other instructors) are amazed that the best athletes cannot remain airborne for a second in a standing jump. This prompts great class discussion. You can challenge your students by saying you’ll award an A to any student who can do a 1-second standing jump! You’ll have takers; but you’ll award no A’s for this feat.