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Activity 7-1: Too Many Bobcats

PLAN

Summary Students learn about the carrying capacity of a specific area by playing a game in which they play the role of bobcats that must gather resources for survival.

Objectives

Students:

\checkmark explain that organisms need certain resources in specific amounts to survive and reproduce.

\checkmark identify the factors that determine the carrying capacity of an area.

\checkmark predict the size of a population based on the available resources.

\checkmark analyze a graph representing a population curve.

Student Materials

Per student

  • Resource
  • Activity Report
  • Sandwich-size plastic bag
  • Masking tape

Per class

  • Colored construction paper: red, green, black, yellow, orange, and blue, cut into 20 rectangles of each color (for a class of 30 students)
  • Large open area-large enough to scatter 120 paper rectangles

Teacher Materials

  • Activity Report Answer Key

Advance Preparation

This activity has been designed for a class of thirty students. Prepare twenty paper rectangles in each of the following colors to represent the organisms listed below:

& \text{rabbits}&& red\\&\text {rodents}&& green\\&\text {fawns}&& black\\&\text {birds}&& yellow\\&\text {reptiles}&& orange\\&\text {water}&& blue

If you have more or fewer students count the number of students in your class and subtract 10. This number represents the number of paper rectangles you will need in each of the colors listed.

Estimated Time One 50-minute period

Interdisciplinary Connections

Math Students calculate survival rates and graph the data.

Physical Education Students will be extremely active during this activity.

Prerequisites and Background Information

None

IMPLEMENT

Introduce Activity 7-1 by having students read the introduction. Discuss what the carrying capacity of a habitat is. Explain that students are going to pretend to be bobcats and determine what carrying capacity really means.

Step 1 Read the rules of the game in Step 1 of the Procedure with the whole class. If the students fail to follow rules, the game will turn into a gathering frenzy and the whole point of the activity will be lost. You may want to point out that these rules are needed for the game but do not necessarily reflect real bobcat behavior. At the end of the activity you may want to discuss what some differences might be between these rules and how real bobcats react in nature. For reference the rules are repeated here:

  • Bobcats do not fight because it takes energy away from the food-gathering activities.
  • Bobcats do not eat more than they need of one kind of food nor drink more water than they need.
  • Bobcats do not snatch food away from other bobcats.
  • Bobcats do not take food from the den if it belongs to another bobcat.

Step 2 Divide the class into two groups of about 15 students each. Set up boundaries to designate each group's habitat area and “den.” Ask each group to go to their den, get a plastic bag, and put their name on it as described in Step 2 of the Procedure. They will keep the plastic bags in the den and return there each time they collect a food or water rectangle and store it in the bag. If you have more than thirty students you may want to divide the class into three groups and set up three habitat and den areas.

Steps 3-6 For a bobcat to survive each round of the game it must obtain paper rectangles in six different colors, which represent water and the five types of food. Any bobcat who fails to obtain the six differently colored rectangles will “die” and be eliminated from the game. It is essential that the students know that only one rectangle (representing one resource) is collected at a time. They must bring each rectangle back to the den to be placed in their plastic bag before collecting the next one.

The total carrying capacity is predetermined by the number of food and water rectangles you place in the habitat areas. At the beginning of round one you spread out 120 food and water rectangles over two habitat areas. After each round you collect the rectangles students have gathered at their dens and spread them out again. In each round the number of bobcats competing for resources increases. The game is designed so that all five bobcats can survive in round one, all ten bobcats can survive in round two but only ten out of fifteen bobcats can survive in round three.

Steps 7-8 After playing the game, have students analyze the graph on the Resource. The graph represents an idealized model for population growth. A population of organisms grows slowly at first and then begins to grow rapidly. Eventually the growth rate slows down and the rate at which individuals are born is the same as the rate at which individuals die. This is a stable steady-state population. The habitat in which the population lives determines the size of the steady-state population. When the resources of the habitat are limited the habitat can fulfill the needs of a limited number of individuals and no more. The carrying capacity of a habitat represents the maximum number of individuals that can be supported.

Conclude Activity 7-1 by reconvening the whole class and discussing what they learned about carrying capacity. Could the “habitat” you simulated “carry” 5 bobcats? (Yes) Could it “carry” 10 bobcats? (Yes) Could it “carry” 15 bobcats? (No) So the carrying capacity of bobcats for the simulation was somewhere between 10 and 15. You may want to have the students answer the questions on the Activity Report in class or as homework.

Extend Activity 7-1 by introducing the following complexities to the game.

  • Add a rule that any bobcat that survives two rounds in a row produces a cub. A bobcat with a cub must collect an additional number of paper rectangles representing food and water for the cub.
  • Emphasize what happens to bobcats that die. Designate a decomposing pile (a specially labeled area) where the dead bobcats remain while their nutrients are recycled into the system.

ASSESS

Use students' answers to the Activity Report questions and completion of the game to assess if students can

\checkmark describe the requirement for resources in specific amounts to survive and reproduce.

\checkmark explain the concept of carrying capacity.

\checkmark analyze and draw conclusions from a population graph.

Activity 7-1: Too Many Bobcats – Activity Report Answer Key

  • Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
  1. Explain what happened to the bobcats in your den for each of the three rounds.
  2. What factors determined whether bobcats survived or not?
  3. What other factors might affect the carrying capacity of a habitat for bobcats? How could you alter the game to include these other factors?
  4. Do you think that the earth has a carrying capacity for humans? Explain.
  5. Analyze the graph on the Resource. How does the growth of the population change?
  6. Explain what is happening to the population in the far right section of the graph. Why does this occur?

Define the Niche of an Animal Students choose a specific animal and investigate its niche by identifying the resources it needs to survive.

Help students pick animals that may live in habitats near your school or ask the class to suggest the animals they find most interesting and list them on the board. Then let students pick from the list or an animal of their own choice. Students can make a poster of their animal in its habitat surrounded by its resources.

Review Questions/Answers

  • Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
  1. What is a resource? Describe three general categories of resources.
  2. Do all organisms require the exact same resources? Give an example or two to support your answer.
  3. Is it possible to have too much of a needed resource? Support your answer with an example.
  4. What is the difference between the habitat and the niche of a plant?

Activity 7-1 Resource: Too Many Bobcats (Student Reproducible)

Population Growth

The graph below illustrates one type of population growth. Study the graph and read the description that explains the pattern on the graph.

When organisms are first introduced into an area, the population grows slowly. Soon the population begins to grow very rapidly. Eventually the growth slows down again until the birthrate is equal to the death rate. The population size stabilizes.

Activity 7-1 Report: Too Many Bobcats (Student Reproducible)

1. Explain what happened to the bobcats in your den for each of the three rounds.

2. What factors determined whether bobcats survived or not?

3. What other factors might affect the carrying capacity of a habitat for bobcats? How could you alter the game to include these other factors?

4. Do you think that the earth has a carrying capacity for humans? Explain.

5. Analyze the graph on the Resource. How does the growth of the population change?

6. Explain what is happening to the population in the far right section of the graph. Why does this occur?

Image Attributions

Description

Authors:

Grades:

6 , 7 , 8

Date Created:

Feb 23, 2012

Last Modified:

Feb 23, 2012
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