Chapter 1

The Nature of Science

Do Now

• Try to write down the steps a scientist might use to solve a problem – this is

called the scientific method.

– Hint – there are 6 steps

1.2 The Scientific Method

• Suppose you knew nothing about science

• How would you explain why it rains???

1.2 The Scientific Method

• If someone didn’t believe your explanation, could you prove it???

• Why or why not???

1.2 The Scientific Method

• Since the beginning of human history, people have tried to explain natural events (like rain).

• Because of limited information, they may have come up with ideas that seem silly to us today.

1.2 The Scientific Method

• We now assume that all events in nature have a natural cause.

• We try to arrange a series of observations or tests to learn what these causes are.

• The goal of science is to understand the world around us and the scientific method is what distinguishes science from non-science.

1.2 The Scientific Method

• The scientific method is a frame of mind that involves curiosity.

• Curiosity spurs a scientist to ask questions.

• The scientific method also includes a refusal to accept explanations without evidence or proof.

• This “prove it” attitude makes scientists investigate ideas and develop explanations.

Steps to the Scientific MethodOrganized Common Sense

1. Observing and stating the problem

2. Forming a hypothesis

3. Testing the hypothesis

4. Recording and analyzing the data

5. Forming a conclusion

6. Replicating the work

Scientific Method Video

• YouTube - Chemistry Music Video 1: The Scientific Method

• 3 minutes

Graphing

• A graph is a diagram representing a system of connections or interrelations among two or more things by a number of distinctive dots, lines, bars, etc

• Graphs have an X axis (horizontal) and a Y axis (vertical)

• It is a great way to present scientific data because it is easier for people to understand than a bunch of numbers

Graphing Activity

• We will start a worksheet on graphing in class and then you will finish it for homework.

• Put 2 graphs per piece of graph paper• Skip question #3

Do Now

• Why do scientists graph their data?• Name 2 types of graphs.• Is the X axis horizontal or vertical?• Is the Y axis horizontal or vertical?

1. Observing and stating the problem

• Observation – leaves change color in autumn• Why????

2. Forming a Hypothesis

• Hypothesis – possible explanation, preliminary conclusion or even a guess about some event in nature

• It gets cold and that causes the leaves to change color

3. Testing the Hypothesis

• Perform an experiment

- In July, take a small tree growing in a pot and place it in a growth chamber set to autumn temperature levels.

- If our hypothesis is right, the leaves should change color.

- If the leaves do change color, would we know if it was definitely due to the temperature?

3. Testing the Hypothesis

• Not really!!!• There are factors other than temperature that are

different between our tree in the growth chamber and a tree growing outside.

• Our tree is growing in a small pot.• Our light is not natural light.• Etcetera

Variable

• A variable is the factor that is isolated and tested in an experiment.

• In a good experiment, all factors other than the variable should be kept the same.

• Our variable is the temperature in the growth chamber.

Types of Variables• Variables are things that may be expected to change

during the course of the experiment.

– The investigator deliberately changes the independent variable. (CAUSE)

– He or she measures the dependent variable (EFFECT) to learn the effect of changing the independent variable.

– To eliminate the effect of anything else that might influence the dependent variable, the investigator tries to keep standardized variables constant.  

Control

• We need a control, which is the part of an experiment that does not contain the variable (temperature)

• Grow a second tree in a pot an place it in a growth chamber also.

• But, set the temperature in this chamber to normal summer temperatures.

• Now, if the leaves change color we can be more sure it was due to the colder temperature.

4. Recording and Analyzing Data

• As you perform the experiment you must collect data by recording observations and information

• In our experiment, we could count the number of leaves that changed color and the time it took for them to do so.

• Then you must analyze the data by putting it in tables and graphs

5. Forming a conclusionYahoo! Video Detail for Why do leaves change color in the fall?

• Now we have to decide if our hypothesis is true.• We look at our data – does it support our hypothesis?• In our experiment, if only the leaves on the tree in the

colder chamber change color, we may decide that we confirmed our hypothesis.

• If the leaves of neither or the leaves of both trees change color, we may reject our hypothesis.

6. Replicating the work

• The original researcher must be able to reproduce the experimental results.

• Other researchers should also be able to reproduce the experiment.

Hypothesis and theories

• Theory – when a hypothesis is tested and confirmed often enough that it is unlikely to be disproved by future tests

• Powerful time tested concept that makes useful and dependable predictions about the natural world

1.2 The Scientific Method

• Galileo was the first scientist credited with using the scientific method.

• He recorded the series of steps he used to investigate falling objects.

• The scientific method is not only used by scientists.• We all use the scientific method every day!!!

Scientific Method Video

• YouTube - The Scientific Method Video

• 3 minutes

Activity – Identifying Variables

• Work in groups of 2• Read each scenario and try to figure out the

– Independent variable

– Dependent variable

– Standardizing variables

– Control Group

**Finish what you can in class and do the rest for homework.

Do Now

• What is an independent variable?• What is a dependent variable?• What is a control group?

A Universal Language – The Metric System

YouTube - Metric & Standard Measurement Systems

Metric System• Science works best when scientists read each other’s

papers, check each other’s experiments, and argue about what results mean.

• To do this they need a universal system of measurement to present their findings.

• Scientists use the metric system of length, volume, mass, and temperature when describing experiments and data.

Metric System

• Decimal system based on certain standards and scaled on multiples of 10:

– Kilo – 1000– Basic Unit– Centi – 1/100– Milli – 1/1000– Micro – 1/1,000,000

Metric System

• Do you know the common metric units??– Length?– Volume?– Mass?– Temperature?

Length

• Meter – basic unit of length in the metric system

• Equivalent to 39.4 inches (a little longer than a yard)– Kilometer (1000 meters)

– Meter

– Centimeter (1/100 of a meter)

– Millimeter (1/1000 of a meter)

Volume• Volume - amount of space an object takes up• Cubic Meter – basic unit of volume for solids in the

metric system• Liter – basic unit of volume for liquids in the metric

system

– Kiloliter (1000 liters)– Liter– Centiliter (1/100 of a liter)– Milliliter (1/1000 of a liter)

Mass and Weight

• Mass – measure of the amount of matter in an object• Weight – a measure of the pull of gravity on the mass• Weight can change – mass never changes (space)• Gram – basic unit of mass in the metric system

– Kilogram (1000 grams)– Gram– Centigram (1/100 of a gram)– Milligram (1/1000 of a gram)

TemperatureCelsius Scale – metric temperature scale

• Water freezes at 0oC

• Boils at 100oC

• Each Celsius degree is 1/100 of the range between freezing and boiling

– Normal Human Body Temperature is 37oC

– Room Temperature is approximately 21oC

Metric System Activity

• Conversion Worksheet

• Finish what you can in class and do the rest

for homework

Do Now

• What is the basic metric unit of measurement for length?

• What is the basic metric unit of measurement for volume of a liquid?

• What is the basic metric unit of measurement for mass?

• What is the basic metric unit of measurement for temperature?

1.3 Science: “Facts” and “Truths”

Fact or Truth

• Scientific knowledge is a constantly changing body of observations

• Many “scientific facts” of the past are now know to be false (the earth is flat, the sun revolves around earth, etc)

• Facts are the best explanations of the world around us developed so far

• Some of the things you learn in this class may sometime be proven false

Fact or Truth

• If a fact is found to be false our knowledge has increased - we have not failed

• Science continues to advance our understanding of the world

How to Study Science

• Don’t try to memorize individual facts – there are too many!!

• Arrange facts in groups – according to subjects• See how things are inter-related• Science is a process – try to see the thinking behind

the experiments we discuss

Science and Human Values

• An important goal of science is to be objective• But, this does not always happen – scientists are

people too!• They have different opinions, emotions, likes and

dislikes– Energy– Animal and human experimentation

• Data can be misinterpreted or misapplied to prove a particular point

Science and Human Values

• Studying science makes us all more informed

• Understanding it decreases the dangers posed by misinterpretation or misleading information– Ex. nuclear power, acid rain, chemicals in food and water

The Spaceship called Earth

• Earth is beautiful when seen from space• Our species has rapidly developed the ability to

change the earth for both the better and the worse• The earth is not a planet without end. It is more like a

spaceship with a living cargo, carrying limited amounts of supplies

• We must take care of what we have and prepare for the future

Activity

• Scientific Method Study Guide• Fill it out using your notes and use it as a study guide