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LESSON DESCRIPTION: Predator vs. Prey
Intern: Duane Krogh
CT:
Day/Grade: 10th grade Biology
Essential Question:
How do predators and prey relationship contributes to limiting factors on populations in an
ecosystem?
STANDARDS/EALRs:
Science: EALR 4 – Life Sciences 9-11 LS2B: Living organisms have the capacity to produce
very large populations. Population density is the number of individuals of a particular
population living in a given amount of space.
Science: EALR 4 – Life Sciences 9-11 LS2C: Population growth is limited by the availability
of matter and energy found in resources, the size of the environment, and the presence of
competing and/or predatory organisms.
a* 7.2.E Represent proportional relationships using graphs, tables, and equations, and make
connections among the representations. (Mathematics connection)
RATIONALE:
The science lesson follows lessons concerning ecosystems and communities. Previously the
students learned the role of climate, what shapes an ecosystem, the world’s major biomes,
and aquatic ecosystems. This lesson will introduce students to populations and factors that
influence and limit their growth. This lesson focuses on the impact of predators-prey
relationship within an ecosystem and how this impacts the population density of both predator
and prey. Students will be able to use this model to compare other limiting growth factors of
competition, parasitism and disease in future lessons. Students will determine a graphical
representation model to analyze their data.
OVERVIEW:
Over the course of 2 days, the students will simulate an ecosystem of prey of M&M’s and
Marshmallows. The students will control 4 different predators, knives, forks, spoons and
toothpicks, which will feed on the prey. Students will record data concerning the type and
amount of prey consumed by each of the predators. Students will calculate the impact of the
predation and the prey, for the next generation of each. Students will conduct 4 rounds of
predation, with the predators and prey populations adjusted between each round.
LEARNING OBJECTIVES
By the end of class, the students will be able to identify density dependant factors that limit
the growth of populations, both predators and prey. Students will be able to contrast the
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different characteristics of the predator, and their impact on the prey. Students will be able to
assess the characteristics of predators that impact the population density of the prey.
Students will be able to calculate, analyze both numerically and graphically, the impact of the
predators.
Students will also be able to identify a graphical representation models for analysis of their
data to make connections and conclusions between predators and prey.
ASSESSMENT [curriculum/student learning/teacher effectiveness]
1. The lesson fits into the unit populations, after a previous unit on ecosystems and
communities. This lesson demonstrates one of the limiting factors on populations within an
ecosystem.
2. Students will be assessed by teacher review of their data worksheets and their lab
notebook write-ups. Students will complete their data worksheets, and transfer their final data
into their lab notebook. Students will be asked to write in their lab notebooks conclusions for
this lab comparing and contrasting the different predators and prey, along and the impact of
the different predators on the different prey.
MATERIALS:
 Data Worksheet
 3 large bags of M&M’s
 3 large bags of small Marshmallows
 Box of toothpicks
 130 paper cups
 Calculators for each group of 4
TEACHER PREPARATION NOTES:
Make copies data worksheet
Get large bag of M&M’s, Marshmallows, toothpicks and paper cups.
Example bar and line graphs for overheads.
Overhead example of data sheet, filled in with example data.
Get calculators for each group
STRATEGIES FOR ACCOMODATING STUDENTS WITH SPECIAL NEEDS:
Students will work in groups, and group members can describe the materials being used, and
provide students will examples of the materials they have chosen.
The Lesson can be geared down and modified for individual students by limiting the number
of predators used in each round.
The lesson can be geared up by having the teacher introducing additional limiting factors
such as a limiting nutrient for the prey.
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SEQUENCE of ACTIVITIES & CONTENT:
Day 1
BELL RINGER ACTIVITY – Warm-up Sheet– 5 minutes
What is a predator?
What is a prey?
Ask the class:
Q. Why don’t we see unlimited amounts of rabbits, birds or squirrels around us?
Q. Are these the same reasons for each of these animals?
Goal or question for the day:
How do predators and prey relationship contributes to limiting factors on populations in an
ecosystem?
Next 5 minutes:
Review with the class the overview of the lab lesson today.
We will simulate an ecosystem with predators and prey.
We will run 4 different sessions where the predators will consume the prey.
Explain they will have a worksheet to fill out for each session.
At the end of each session, we will calculate the impact of this round on the population
density of the predators and prey, to begin the next round.
Explain what type of predators we have, (knives, spoons, forks and toothpicks)
Explain what type of prey we have, (M&M’s and Marshmallows)
ACTIVITY (10 minutes small work group)
Handout worksheets to every student. Explain the activity and what each student will do.
They will each fill out a worksheet.
Break into groups of 4.
Explain the process of the lab.
Each student will choose two predators, for a total of 8 per group
Each group will receive 30 M&M’s and 30 Marshmallows, placed on their table.
Each student will receive 4 paper cups.
Students will label the cups “knife”, “fork”, “spoon”, “toothpick”
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Predator-Prey Rounds - Next 35 minutes:
At the start of the round, announced by the teacher, the students will try and obtain as many
prey as possible with their two predators.
For each prey consumed, the students will place them into the appropriate paper cups.
At the end of the round, the students will record the number of prey consumed by each type
of predator into the appropriate boxes on the worksheet.
Students will total the number of prey consumed, and the amount that survived.
Students will then calculate the number of prey to begin the next round.
The prey will double at the end of the round.
Teacher to provide additional prey, however some prey may be “recycled” from the
paper cups. Otherwise, the teacher may provide more prey from their stock bags.
Students will calculate the number of predator by each type to begin the next round.
The worksheet has boxes to help determine these values. The number of predators for
the next round is determined by dividing the amount of prey (both M&M’s and
Marshmallows) by the total prey eaten by all of the predators, times 8. When the total
number of predators is determined, there should always be no more than 8 total
predators, but there can be a different amount of individual predators.
The finalized number of prey and predators are entered for the second round.
The process is repeated for rounds 2, 3 and 4.
At the end of round 4, the students do not need to calculate the number of predators or prey
for additional rounds.
LAST 10 MINUTES:
End of day 1 of the lab.
Clean up for the lab.
Walk through classroom verifying that students have completed their worksheets, and are
ready for the analysis phase of the lab on Day 2.
Students may consume the prey if school rules allow.
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Day 2
BELL RINGER ACTIVITY – Warm-up Sheet– 5 minutes
What is extinction?
What is a limiting factor?
Discussion Period – 15 minutes
What was similar about the predators?
What was different about the predators?
What was similar about the prey?
What was different about the prey?
Which predator consumed the most prey, and why?
Did each group have the same results? Explain why or why not?
If any prey became extinct, what do you think were the reasons for their extinction?
What other factors could you think of that might also affect the size of the prey population?
What impacted the population of the predators, and why?
What other factors could you think of that might also affect the size of the predator
population?
Graphing Data – 10 minutes
Present different types of graphs on overhead, line graphs and bar charts.
Q: What kind of information does each graph provide?
Q: What information about the predators and prey would be better illustrated with a graph?
Which type of graph?
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Lab Notebook Work Time – 20 minutes
Lab Notebook Assignment
1. Create a data table showing beginning amount of prey and number captured by each
predator. Number of prey survived. Number of predator and prey for the next round.
2. Develop a graph showing relationship between predator and prey.
3. Write conclusions explaining what happened to the prey, and the predators, and why
do you think this happened?
Final clean-up and any questions – 5 minutes
REFLECTION: