Grade: Grade 5 Subject: Science Unit: Ecosystems & Energy Flow SAT: ProblemSolving+DataAnalysis ACT: Science

Ecosystem Investigation Lab

Learn

Scientists study ecosystems by making observations, collecting data, and analyzing patterns. In this lesson, you will conduct investigations to explore how energy flows through ecosystems and how organisms depend on each other.

What is a Scientific Investigation?

A scientific investigation is a process of asking questions, making predictions, collecting data, and drawing conclusions based on evidence. Scientists use investigations to understand how ecosystems work and what happens when they change.

The Scientific Method in Ecosystem Studies

When studying ecosystems, scientists follow these steps:

  1. Ask a Question: What do you want to find out about the ecosystem?
  2. Make a Hypothesis: What do you think will happen? (An educated guess)
  3. Design an Investigation: Plan how to test your hypothesis
  4. Collect Data: Make observations and record measurements
  5. Analyze Results: Look for patterns in your data
  6. Draw Conclusions: What did you learn? Was your hypothesis correct?

Safety First!

When conducting outdoor investigations: Stay with your group, wash hands after touching soil or organisms, don't disturb wildlife, and always return organisms to where you found them.

Investigation 1: Schoolyard Ecosystem Survey

Schoolyard Food Web Investigation

Objective

Identify producers, consumers, and decomposers in a local ecosystem and create a food web showing their relationships.

Materials Needed

  • Clipboard and paper
  • Pencil or pen
  • Magnifying glass (optional)
  • Camera or phone for photos (optional)
  • Data recording sheet

Procedure

1
Choose Your Study Area: Select a 10-foot by 10-foot section of the schoolyard. Look for an area with plants, soil, and possibly some shade.
2
Identify Producers: List all the plants you can find (grass, trees, flowers, weeds). These make their own food through photosynthesis.
3
Find Primary Consumers: Look for herbivores (animals that eat plants). Check under leaves, on plants, and in the grass. Examples: caterpillars, grasshoppers, rabbits, squirrels eating seeds.
4
Spot Secondary Consumers: Search for animals that eat other animals. Examples: birds eating insects, spiders catching flies.
5
Locate Decomposers: Check damp areas, under rocks, and in soil. Look for mushrooms, fungi, earthworms, and pill bugs.
6
Record Your Data: Count how many of each organism you find and note what each one eats or what eats it.

Virtual Ecosystem Simulator

Use this simulator to explore what happens when population sizes change in an ecosystem. Adjust the sliders and observe the effects!

Ecosystem Balance Simulator

Change the population of one organism and see how it affects the entire food web!

50
25
10
🌿 Grass 50
🐰 Rabbits 25
🦊 Foxes 10
⚖️ Balance Stable

Examples

Example Investigation: Effect of Removing Producers

Question: What happens to an ecosystem if most of the grass is removed?

Hypothesis: If the grass is removed, then herbivore populations will decrease because they will have less food.

Sample Data Table

Week Grass Coverage (%) Rabbit Population Fox Population
0 (Start) 100% 50 12
1 25% 45 12
2 25% 35 11
3 25% 22 9
4 25% 15 6

Conclusion: The data supports the hypothesis. When grass was reduced to 25%, rabbit populations decreased from 50 to 15 over four weeks. Fox populations also decreased from 12 to 6 because there were fewer rabbits to eat. This shows how changes to producers affect the entire food web.

Key Observation

Energy flows from producers to consumers. When producer populations decrease, it creates a ripple effect through the entire ecosystem. This is called a trophic cascade.

Practice

Answer these questions about ecosystem investigations.

1 A scientist wants to study how pollution affects fish populations in a lake. What should be the FIRST step?
A Count all the fish in the lake
B Ask a question and form a hypothesis
C Write a conclusion about pollution
D Add more pollution to the lake
2 In a schoolyard ecosystem study, a student found 15 grass plants, 8 caterpillars, 3 birds, and 5 mushrooms. How should these be classified?
A Grass (Producer), Caterpillar (Primary Consumer), Bird (Secondary Consumer), Mushroom (Decomposer)
B All are producers because they are all living things
C Grass (Consumer), Caterpillar (Producer), Bird (Decomposer), Mushroom (Consumer)
D All are consumers because they all need energy
3 A student hypothesized that removing foxes from an ecosystem would cause rabbit populations to increase. Which data would BEST support this hypothesis?
A Rabbit population stayed the same after foxes were removed
B Rabbit population increased from 50 to 85 after foxes were removed
C Rabbit population decreased after foxes were removed
D Fox population increased after rabbits were added
4 Why is it important to count organisms multiple times during an ecosystem investigation?
A To make the investigation take longer
B To identify patterns and changes over time
C Because organisms don't move
D To use more paper
5 A pond ecosystem has 1000 units of energy from algae (producers). About how much energy would be available to fish (primary consumers)?
A 1000 units (all the energy transfers)
B About 100 units (10% rule)
C About 500 units (half the energy)
D 0 units (no energy transfers)
6 During a field study, a student observed that areas with more trees had more birds. What type of relationship does this suggest?
A No relationship - trees and birds are unrelated
B Negative relationship - more trees means fewer birds
C Positive relationship - more trees may provide more food and shelter for birds
D Random relationship - it changes every day
7 What is the purpose of a control group in an ecosystem experiment?
A To control the weather during the experiment
B To provide a comparison that shows what happens without any changes
C To add more variables to the experiment
D To make the experiment more difficult
8 A student's data shows that when caterpillar populations increased, plant leaves had more holes. This is an example of:
A A cause and effect relationship
B A coincidence with no connection
C Plants making more caterpillars
D Decomposition in action

Check Your Understanding

Scientific Method

Question, Hypothesis, Investigation, Data, Analysis, Conclusion - the steps scientists use.

Data Collection

Recording observations and measurements accurately to find patterns in ecosystems.

Variables

Factors that can change in an experiment. Control groups help compare results.

Trophic Cascade

When changes to one species affect multiple levels of the food web.

Field Study

Observations and investigations conducted in natural environments.

Evidence-Based Conclusions

Using data to support or reject hypotheses about ecosystems.

Key Takeaways

  • Scientific investigations help us understand how ecosystems function
  • Data must be collected multiple times to identify patterns
  • Changes to one organism can affect the entire food web
  • Conclusions must be based on evidence from data

Next Steps

  • Conduct a schoolyard ecosystem survey and create your own food web
  • Design an investigation to test how sunlight affects plant growth
  • Learn how to display your data using graphs in the next lesson
  • Practice writing scientific explanations using evidence