LISA M. MARTIN-HANSEN

s an elementary teacher struggling with a way to incorporate an inquiry approach to teaching in my classroom, I began to ~efioe a crayfish unit on@-

ly found in an ESS (Elementary Science Study) crayfish module (Educational Development Center 1966). M y desire was to have students learn both process and content skills h u g h both a guided and an open-inquiry approach. Later, I used the same investigations with my eighth-grade life sci- ence students and even with my college-level preservice teach. All the students marveled at the behavior of the small, brown lobsterlike creatures. The students participat- ed in a guided experience with crayfish, asked questions, and then did investigations related to their questions. Simul- taneously, they concentrated on specific standards of the Iowa City Community School District that a~ based upon the National Science Education StMdards. Science as inquiry, Content Standard A states that “As a result of activ- ities in grades 5-8, all students should develop abilities nec- essary to do scientific inquiry and understandings about sci- entific inquiry.’’ Life science Content Standard C states that “As a result of their activ&ia in grades 5-8, all students should develop understandings of structure and function in . . . regulations and behavior, and populations and ecosys- tems” (National Research Council 1996). My mostrecent inquiry approach that seems to work well

is called a “ m u p M ~ approach. Many elementary and middle school science t e a c h in the Iowa City Com-

LlSA M. MA#T1IwIANSEN is an assistant professor of ehca- tion at Dmke University in Des Moines, Iowa. She teaches ele- mentary science teaching methodr and middle school education courses.

munity Schod District successfully use wpkd-ioquiry cycles in their classrooms. Corrpled-inqw is a combina- tion of guided-inquiry and open-inquiry, with an application used for assessment purposes. In five or six class periods using a few, easy-to-find materials, students can investigate crayfish in the classnw>m.

Background Craytish (also commonly known as crawdads or craw-

fish) can be found on every continent of the world except for Antarctica and Africa, although some fossils of crayfish have been found in Antarctica. Over 590 species exist in the world; nearly 70 percent (404) of those live in North Amer- ica. Crayfish fossils date back to the Triassic period (approxirnately 225 million years ago) in Utah, Arizona, and North Carolina.

During the day, crayfish spend time hidmg under rocks and vegetation. Many dig burrows into the beds or banks of ponds or streams. when the surface water h z a or when there is little wa&cr due po drought, crayfish will stay in these burrows for weeks at a time. Usually, the f d e will lay her eggs while she is in a burrow and mmah t b e ~ until they have hatched. After the oggs have hatched, the young cling to the swimmemrrua (underbelly) of MO~MX cray- fish for protection frmn predators. To d e f d tkms~lves against predaturs or other crayf’ish, craytish cat^ swim back- ward very quickly; they c811 also leave behind a pincer dm- ing a fight. When the crayfish molts, its pincers gradualiy regenerate. The best way to collect crayfish in a stnam or freshwater

lake is to use meat (fish heads small pieces of chicken, or a piece of hotdog) as bait and a %” mesh net. Because crayfish prefer the dark, the bcst time to catch them is at dawa or at

36 SCIENCE ACTIVITIES Vol. 38, No. 2

dusk. Put the meat in a shallow part of the water along the shore by a rocky area or by a place that has some vegeta- tion. When the crayfish emerge, catch them with the net. It is easier to catch them by moving the net from tail to head because crayfish will “swim” backward by flapping their tails beneath them.

Materials

Plastic tubs (shoebox size) (for student pairs to take crayfish

Small plastic swimming pool or large aquarium Aquarium bubbler to supply air for the swimming pool/

aquarium (Available at pet stores or large department stores that carry pet supplies such as Wal-Mart)

Food (e.g., earthworms, pieces of hot dog, or crayfish pel- lets [sold by Carolina Biological])

Crayfish-one for every two students plus a few extras in case some do not survive. Most bait shops can get cray- fish within a couple of days if crayfish are in season (spring, summer, and fall in the Midwest). The cost is approximately $4/dozen. If students like, they can catch crayfish with a net by dangling a piece of hot dog on a string in some freshwater lakes and streams. Carolina Biological also supplies crayfish (see Resources).

to their desks)

Bricks and rocks to provide shelter for crayfish Construction paper or cardboard Aluminum foil Chart paper (to make 2 charts) Science notebooks Worm scent, fish scent, and crayfish scent Q-tips Small pail

Crayfish Care

The following tips may aid you in caring for your cray- fish and save you from making some of the mistakes I did:

Let tap water in the pool or aquarium sit for 24 hours to bring water to room temperature and to dissolve the chemicals in the water that may harm crayfish. Crayfish seem to do well in water that is nearly level with the tops of the bricks and rocks. If crayfish do not get enough air from the water through their gills, they will crawl on top of the bricks and rocks for air. Although they can survive for sev- eral hours by doing so, you will need to aerate the water to prevent them from dying.

Make sure that your bubbler is working well so the crayfish have plenty of air to breathe. Having two bubblers is even better. Place the bricks on their sides to allow cray- fish to perch in the holes of the bricks. Crayfish are very ter- ritorial (do not tell the students this; let them discover it on their own) and like to have their own specific hiding places.

Keep the crayfish well fed by feeding them with a small chunk of hot dog or other piece of food once every day or every other day. Remove food remains after an hour or so to keep the water clean.

Place just enough water in the students’ containers to

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reach the crayfish’s back when it walks around. Crayfish can survive for approximately an hour in this environment.

The Process - Assessing Prior Knowledge Preparation

A good way to find out what students know (and do not know) about a topic is to have them make a K/W/wL chart adapted from the KWL teaching model created by Donna Ogle (1986). This teaching model was developed to foster active reading of expository text. First ask students, “What do you already know about crayfish (K)?” “What do you want to know (W)?’ and “How could we find out (H)?” After the investigation is finished, students can complete the “What have we learned (L)?” category.

Bring the crayfish into the classroom and set up two plas- tic swimming pool environments. After feeding the crayfish a few small pieces of a hot dog, make sure that the water is shallow enough for them to reach additional air by crawling up on the rocks and bricks. Remember that it is important to have a good aquarium bubbler and bricks and rocks to serve as hiding places for the crayfish.

Procedure The “Hook” to Interest the Students Day I

1. Have the students bring their science notebooks (5 sheets of notebook paper or paper folded in half and stapled to make a small book) to the back of the room and spend time watching the crayfish in their habitat without touching them.

2. Remind the students of the different ways to take data. They could plot where crayfish move on a piece of graph paper or write descriptive notes about the crayfish and their artificial habitat. Writing down questions as they observe will help the students focus specifically on the questions related to “What do we want to know?’

3. Ask the students to make simple observations, draw pictures (being very still to not disturb the crayfish), and write descriptions of the crayfish.

4. After recording observations (drawings of where the crayfish were in the pond or comments about their behavior), allow the class to share their observations. Ask the students to take a few minutes to record any questions they might have about their crayfish. Involve more students in the sharing process by having pairs of students create a short list. Add these questions to the “What do you want to know?’ list.

Days 2 and 3

1. Have the students in their science notebooks make detailed drawings of the crayfish. Let each group share its questions with the class and next to each question make a note of how to find out that information. For example, “Can we find this out by watching the crayfish?’ (observa- tion), creating an investigation or test (that would not be harmful), or seeking the information in a book or on the Internet? Mark the questions with an “0’ (observation), “I” (investigation), or “R’ (resource).

Summer 2001 SCIENCE ACTIVITIES 37

Guided Inquiry Preparation

the bottom while feeding the others so some hungry crayfish for later investig question, you should choose one from the list or choose one that is not listed. This will help the students gain additional experience with the crayfish and have more time to think about other questions to investigate. Your selection of the first question also helps target a specific district standard.

Do the next step in one of two ways. You could guide the class in creating a process for investigating the crayfish, or student pairs could create their own designs. At the beginning of the year, I had the class create the design together, which gave us time to learn about how to design a “fair test.” If the unit is taught in the spring, the students will already know how to create a fair test. In a fair test, as many variables as possible are held constant so that the students can test for that one variable. (This is necessary if the stu- dents choose to pursue an experiment rather than an observation task.)

While they observe and test, tell the students to be sure that there is enough water in their tubs to cover most of the crayfish’s body. If the water too deep, however, the crayfish can drown because there is no bubbler to add additional

In the final part of the guided activity after the students are finished with their testing, have them report their

investigation designs and results to the class. Encourage the students to question each

other about the results. For example, could their designs have been made more carefully? How did they obtain

data? Did each student act consistently from group to group? How else could they create the investigation? Have the class pool

the results and decide whether they can make any generalizations about crayfish behavior or whether they need to perform addi-

tional tests to obtain more data. If additional tests are necessary, let them choose to do these in the

Place a few crayfish in a small pail with a little water in

next component of the coupled-inquiry.

Student Investigations (Open Inquiry)

For the first example, have the stu- dents write the design clearly so the explanation could be given to a differ- ent classroom of students and allow them to do the same investigation in the same way. Emphasize that scientists need to create investigations that can be repeated by others to check for accuracy. For this reason, try to create carefully designed tests that others can replicate.

Second, as a class, decide upon these components: an explanation of the investigation that includes the question being asked and the procedure for finding answers to it, along with the needed materials. After a procedure is agreed on, have the students decide how to record data. Is a chart neces- sary? A diagram? Is time a factor? How can we use mathe- matics to express data? Finally, perform the investigations, record results, and then have the students write their final thoughts about the test and share them with the class. If the question to be investigated is not an observation but an exper- iment, a fair test (the experiment) should also include a “con- trol.” A control represents the conditions in which no experi- mentation is done versus the variable of the experiment.

Following a quick review on how to safely pick up a crayfish (stand behind the crayfish and put your thumb and index fingers on its back and sides), your students will be ready to start. Be sure to stand far enough back so the cray- fish cannot pinch you. Do not require the students to pick up the crayfish if they are uncomfortable doing so. Small aquarium nets work well in transporting crayfish from one place to another. If a particular class has difficulty working together, assign specific roles. In other classes, the group role assignment may not be a factor.

Days 4 and 5 1. Revisit the list of questions. Ask the students whether

they can think of other questions that could be tested. Direct the student pairs to choose two questions to investigate along with an additional observation or resource question and then record these in their science notebooks.

2. In preparation, purchase different materials that stu- dents can use for their tests. Encourage them to bring their own materials (upon your approval to ensure that they are not harmful to the crayfish) from home, too.

You can refer to the following list for some examples of popular investigations and optional materials to use for the investigations:

Scent Attraction: Worm scent, crayfish scent, and fish scent from your local fishing shop (You can use Q-tips to absorb the liquid for the test). Have the students devise ways to test the scent the crayfish prefers.

Food Preference: Oranges, lettuce, hot dogs, canned corn, carrots (students can try other food items if they wish). Ask the students to create tests to determine whether crayfish prefer one food to another. (To do so requires NOT feeding crayfish for approximately 2 days; therefore, it is good to set some crayfish aside for this purpose to have hungry crayfish).

Light v. Dark: Construction paper or cardboard (to be put partially over the plastic tub to create a shadow). Which environment do crayfish prefer?

Temperature Preference: The materials will depend upon student design although aluminum foil comes in handy to create different “pools” for crayfish. Because crayfish are cold-blooded, you need to make sure that the plan the stu- dents create will not harm the crayfish (e.g., the water should not be icy or greater than 90 degrees Fahrenheit).

38 SCIENCE ACTIVITIES Vol. 38, No. 2

House v. No House: Rocks or bricks or similar materials. Do crayfish prefer to stay in a shelter?

3. Have the students plan their new investigations and them check them with you (you can initial student plans after you look over their designs). Ask them questions about the design of their investigations to help them clarify and modify them if necessary. If changes need to be made, allow the students time to revise their plans until they are satisfactory. A helpful additional step is to have one group check another group’s design and ask clarifying questions.

4. Carry out the investigations. You will find that some groups finish before other groups. If so, you can direct the finished groups to begin a second investigation or observa- tion testing their second question. If there is no time for a second investigation, have the students look in books and other resources to find other questions that cannot be inves- tigated by experimentation. Poll the class to see which tests it chose to do and then record each experimental question on your second piece of chart paper. As tests are finished, have the groups record their findings on the chart paper.

Inquiry Resolution

With the information you obtain, make generalizations about crayfish behavior and compare these findings with the information found in books and the Internet. After checking the resources, have the students reevaluate their findings and refine their explanations to logically support their investigation conclusions. Discuss why classroom data might be different from what a book predicts. Ask whether a more refined investigation could be done. What would the conditions need to be?

An important part of the students’ reflection includes having them ask themselves how they could design their investigations differently or what they could have done to make their investigations better.

Assessment through Problem Solving (Application)

Day 6

Choose one of the questions to be investigated and change it into a problem-solving activity in which you can assess students in their application of science knowledge gained through the guided and open-inquiry process. For example:

Original question: Do crayfish prefer the light or the

Problem-solving activity: Create an environment that dark?

demonstrates the lighting conditions that crayfish prefer.

Further Questions to Continue the Cycle

Encourage students to continue to ask additional ques- tions. Doing so will lead to new investigations (observations or experiments) that will increase the students understand- ing of crayfish behavior.

Conclusion

The coupled-inquiry model has helped me to accomplish my goals and objectives as a teacher in addition to allowing my students the freedom to design their own investigations, thus satisfying both my students and me. The National Sci- ence Education Standards refers to inquiry as the “central strategy for teaching science.” By choosing the first ques- tion for my students to investigate, I ensure that the partic- ular standards I am aiming for will be reached. This does not mean that the students do not read about crayfish or that I do not teach crayfish characteristics. However, inquiry is what actively engages the students and makes them think for themselves. Inevitably, the students select questions that will also address other standards and benchmarks in a hands-on, minds-on fashion.

Resources Buck, M. W. 1958. Petsfrorn the pond. Nashville, Tenn.: Abing-

don. Carolina Biological. http://www.carolina.codteacher.htm. Cus-

tomer Service: (800) 334-555 1. Dunkhase, J. A. 2000. Coupled-inquiry: An effective strategy for

student investigations. Presented at the Annual Meeting of the Iowa Science Teachers Section of the Iowa Academy of Sci- ence, Des Moines, October 26, 2000, unpublished manuscript.

Ricciuti, E. R. 1994. Crustaceans. Woodridge, Conn.: Blackbirch Press.

References Educational Development Center. 1966. Elementary science study.

National Research Council. 1996. National science education

Ogle, D. 1986. A teaching model that develops active reading of

Newton, Mass.: The Educational Development Center.

standards. Washington, D.C.: National Academy Press.

expository text. The Reading Teacher 39(2): 564-70.

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