Biology - Grade 10

WHAT	Population Size and Food Foraging/Winter Survival
BIG IDEA	Natural selection influences populations. Environmental forces shape which animals survive and are therefore able to reproduce.
ESSENTIAL QUESTION	How does the environment influence which individuals survive to reproduce?
CONTENT STANDARD	Biology/Life Sciences 6. Ecology - Stability in an ecosystem is a balance between competing effects. As a basis for understanding this concept: 6.c Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.
SKILLS and STRATEGIES	Working in a research team as part of a collaborative group, collecting and tabulating data, graphing experimental results, organizing and classifying data, and analyzing and predicting (inferring) from data, role playing
ASSESSMENT	Graphing results of actions Written summary of investigative findings

The lesson

Background
Populations of animals are limited by the amount of food available. When food supplies become limited, the population must reduce in number. The reduction may be due to individuals leaving the area or by dying of starvation. Often, individuals are not able to leave an area, so they must compete for a limited food supply. Which ones survive and for how long may have an impact on which traits may be passed on to the next generation. Scientists learn about this through a variety of methods that include observation of animal populations.

Objectives
Students will be able to predict how environmental forces shape which animals survive and are therefore able to reproduce. Students, after participating in this activity, will be able to graphically illustrate selection pressure and describe how natural selection influences populations.

Simulation Activity and Competition (Role Playing)
To demonstrate these phenomena, the following conditions are presented:

1. Some students will act as famous zoologists, scientists investigating a particular variety of a species.
2. All other students represent an animal that must forage for food.
3. Food may only be collected with the “mouth” tool used as it is designed.
4. A minimum of five complete food items must be "eaten" each "day."
5. To be "eaten," the food must be collected with the “mouth” and placed in the storage container carried by the student.
6. If more than five food items are "eaten" in one "day," one half of the extra pieces may be kept for the next "day."
7. All numbers are rounded down. This simulates the food storage capacity of the animal. Example:  8 beans are found. Five are "eaten." Out of the three extra, one and a half should be able to be kept, however, one and a half is rounded down to one bean kept for the next "day."
8. One "day" lasts less than one minute long to start with but as time goes by, each day is shorter. This represents the length of days from summer to winter. When the teacher announces that the day is over (night has begun), all feeding must stop immediately.
9. Feeding will last about 20 "days" or until the last animal is alive.
10. An animal is considered to have starved to death after three "days" in a row of not "eating" enough food.

Procedure (for Students)
Role: Animals under observation

1. Get a container (stomach) to use to hold the food items you have collected.
2. Get a “mouth” and report to the famous scientist that is observing your kind of animal.
3. Get a clipboard, put your name on this paper, attach it to your clipboard and give both to your famous scientist.
4. Go with the teacher to the "feeding" area and give your clipboard and paper to your scientist.
5. When the go signal is given, begin to search and "feed."
6. When the stop signal is given, immediately stand or be penalized by losing at least two pieces of food.
7. Return to the designated area to count, record, and turn in the food to your famous scientist.
8. When three days in a row have elapsed without sufficient food, the animal you represent has died of starvation so you can no longer hunt for food.

Analysis of Data

1. For your animal, make a graph of the DAY (x-axis) versus the FOOD COLLECTED (y-axis).
2. Draw a vertical red line across your graph at the point of your death.
3. Study your graph and on that paper, answer questions 1-4 from the conclusion questions below..
4. Give your graph and answers to your famous scientist.

Conclusion

1. How many days of winter did the animal represented by you survive?
2. How many days of winter did the animal represented by you have insufficient food?
3. What survival strategies did you use to help your animal survive?
4. Write a summary of what has been learned about population size, food availability, and individual survival.

Role: Famous Scientists
It is your job to help your animals determine how much food to keep, collect the correct amount of their food and record the number of beans turned in each day.  Each animal should have a food data table.  Record the correct amount of food items turned in daily for each of your animals. After winter, help your herd of animals with their graphs. When they are done, collect their graphs and produce one graph showing the total number of days survived for each of your animals. Arrange your animals from best feeder to worst feeder. Then use your group data to answer the following questions. Next, meet with the other scientists and produce one graph that compares the collected data from each group. Submit your single combined graph. Finally, put your graph on top of the other graphs and submit the entire package.

Herd Conclusion

1. How many days of winter did your animals survive?
2. What was the shortest, the longest, and the range of days for your group?
3. What survival strategies did they use to help them survive?
4. Write a team summary of what has been learned about population size, food availability, and individual survival.

Strategies for differentiation

HOW
Content	Process	Product
Population size in an ecosystem fluctuates due to certain causes.	Students practice role playing and scientific investigation techniques in a simulation activity.	Students graph their findings for each "day" of the activity. Results are compiled and analyzed. Students summarize and make predictions (inferences) based on the results.
Pre-teach science vocabulary words, using objects or pictures as appropriate. Focus on language for body parts and functions related to eating, investigative procedures, graphing skills, and relationship of roles in simulation activity.	Review major concepts using accessible words, pictures, and diagrams. Chunk learning and break up steps in process into manageable parts. Group students in lab mixed ability teams to prepare for the lab exercise and assign cooperative team tasks. Demonstrate the lab exercise. Check for understanding frequently to monitor frustration. Observe students during lab, reinforce vocabulary. Have students describe what happened.	Review graphing tasks. Use multiple ways to assess understanding (orally, pictorially). Have students write 1-2 sentences about the lab experience using the key vocabulary and supplemented with illustrations. Results are graphed, cooperative team work is turned in.