Desert Dwellers (2 Day Lesson)

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Objective

SWBAT recognize cause-effect patterns among fluctuations in wildlife populations.

Big Idea

Wildlife populations are not static. They constantly fluctuate in response to a variety of stimulating and limiting factors. Populations of animals are continually changing in order to maintain equilibrium in an ecosystem.

Engage (Day 1)

10 minutes

*This lesson has been adapted from a Project Wild lesson, entitled, "Oh Deer!" I have revised this lesson to meet the age level of my students and to reflect the desert ecosystem in which we live. This lesson can be followed as it is written, or you can easily adapt it to meet the needs of your region.

I begin the lesson by having students turn to a partner and each take turns listing two of the four basic needs provided by a suitable habitat. (We have learned about this in a former lesson, Habitats - It's a Seller's Market.) After providing 1-2 minutes to review, I play the cartoon below.

After watching the video, I ask the students to think about how the coyote and/or the roadrunner are trying to meet their four basic needs I provide a minute or two of think-time and then call on random students to explain their thinking. As the students provide their responses, I call randomly on others to add to what they student before them has said. (This holds all students accountable for engaging in the discussion and for actively listening to their peers.) I ask the students to think about the many ways this cartoon could have ended differently. For example, what would have happened if another coyote showed up - one that was faster, smarter, and hungrier? We brainstorm a few ideas, as well as their possible consequences, and record them on the board.

Before starting the next part of the lesson, I move the kids outside to a field next to our playground. While it can be done indoors, I find that it is not only more fun to complete outside, but it also provides more authenticity. Our goal for the next activity is to replicate the natural environment, and it is difficult to do so from inside the classroom!

Explore

30 minutes

Before explaining the activity, I have students count off in fours. (Prior to the lesson, I have marked two congruent squares (approx 6 ft x 6 ft) on the ground, about 10 to 20 yards apart, with eco-friendly spray chalk.) All of the "ones" stand inside one square, and all of the "twos", "threes", and "fours" stand inside the other.  All of the ones will become the "roadrunners".  I remind the students that all roadrunners, like any animals, need a suitable habitat, and must find food, water, and shelter in order to survive. Throughout the activity, the roadrunners will need to find these components. 

I give each roadrunner  one of three colored cards - red, blue, or yellow. Each card has a picture of a roadrunner on it that I have printed on the card. When a roadrunner is looking for food, it should hold at the red card. When it's looking for water, it holds up the blue card. When it is looking for shelter, it holds up a yellow card. The students who are the roadrunners must find all three components in order to stay alive. 

The remaining students will each be "food", "water", or "shelter". Students depict which component they are by holding up a corresponding colored card that matches the ones held by the roadrunner. Their cards do not have labels, but no pictures on them. (This allows everyone to identify them as habitat components and not roadrunners.) I try to evenly disperse these at the beginning of the game, making sure there are at least a few of each component.

Players start with their backs facing the opposing group.  When the students are ready, I blow a whistle and the fun begins. Each roadrunner and each habitat component turn to face the opposite group, holding their signs clearly.  When a roadrunner sees the habitat component they need, they should run to it and hold hands, signifying they have met that need.  The roadrunner then returns their card and takes another colored card from me, and tries to capture another one of the habitat components that they need, all while staying connected to the people they have already captured.

In order to survive and reproduce, the roadrunner must collect all three components of a habitat during a round.  If they are successful in collecting all three components, the students they have captured all become roadrunners, signifying that the animal has been able to reproduce and care for their young. Any animal that fails to find its food, water, and shelter dies and becomes part of the habitat. 

If more than one roadrunner reaches a habitat component, the student who arrives there first survives. If a habitat component is not captured during during a round, it stays where it is for the next round. It can, however, change its component at the end of the round.  (Science / Engineering Practices: Develop and Use Models)

I have 2-3 students record the number of roadrunners at the beginning of the activity and at the end of each round. The rounds last as long as it takes for all roadrunners to find the needed components and return to their shelter, or until all of at least one component has been taken and the roadrunners can no longer find what they need. We continue this activity for approximately 15 rounds. (This usually takes about 45 minutes.)

*I allow the students who are "food" to walk or skip away from the roadrunners, simulating how prey may try to get away from their predators in real life. However, "water" and "shelter" must stay in one place. I do not let students run while playing the game, as it can create chaos and kids may end up getting hurt.

Explain

30 minutes

After completing 15 rounds, we return inside and view the data over the document camera. I explain to them that each round in the game signifies one year in the desert. Each student then creates a line graph that shows the number of roadrunners that survived during each year. (Depending on the experience of your class, you may want to provide a graph template or draw a blank graph and display for the students, so they know how to create and label it correctly.)

Once the graphs are completed, we come back together as a class to discuss the activity and analyze the data. I encourage them to talk about the experience, what they observed firsthand throughout each round of the game and afterwards in the graphs we have created.  We discuss the cause/effect relationships that led to fluctuating populations. (Cross cutting concept: Cause and effect relationships may be used to predict phenomena in natural or designed systems.) We also spend time comparing/contrasting this activity to what happens to the actual roadrunner population in our deserts.

I ask the students to summarize some of the things they learned from this activity,  prompting with questions such as:

  • How were the first few rounds of the game different than the middle? The last?
  • What are some "stimulating factors" that might increase the population of a species?
  • What are some "limiting factors" that inhibit the survival of animals?
  • How do these factors affect competition within a species?
  • Do you think the fluctuations we noticed in the roadrunner population throughout the game are the same in the actual desert? Why?
  • Are wildlife populations static (steady) or dynamic (changing)?
  • How would the situations we encountered in the game be similar to the natural environment? How are they different?

Elaborate (Day 2)

40 minutes

We return outside to begin day 2 of the lesson!  We play the same game as we did the day before, with a twist. I introduce a predator (in our case, a coyote) into the simulation.  The coyote carries the same red, yellow, and/or blue card to signify their habitat needs. They start in a designated "predator den" area off to the side of the playing area, and are released approximately 10 seconds into the start of each round.   Once a roadrunner is caught by a coyote, it is taken back to the predator den.  The captured roadrunner now becomes a coyote as well, signifying that the predator was successfully able to meet its own habitat needs.

Coyotes who fail to collect each item will die and become a habitat component. Similar to yesterday, I have a student collect data on the roadrunner population. I also have another student collect data on the predator population. We create another graph for this information as a class (to save time) and discuss similarities and differences from the first set of data we collected. I ask the same questions I did the day before, adjusting them to analyze the effects of the predator-prey relationship on the populations of both species.

Evaluate

20 minutes

As a final evaluation of my students' understanding of the cause-effect relationship in a habitat, I administer the Desert Dwellers Assessment. This document contains a line graph that looks similar to the ones we created, both independently and as a class. The one I distribute contains units and labels, but no title. Students will select an animal population that this graph could represent and answer the questions based on the animal they select. (Science / Engineering Practices: Analyze and Interpret Data)