Lesson Plan: Using a Simulation to Understand Ecological Succession


Materials

Prep Steps
  • Prior to this lesson, ask students to bring two photographs of themselves to class: one baby photo and one closer to present day
  • Review understanding goals and background information
  • Read the lesson plan
  • Reserve space in a computer lab or arrange another place where students can access the online simulation
  • Print one simulation worksheet per student

Analyze Thinking


Step 1: Connect Backward with Personal Photographs
Students will have an easier time understanding a complex phenomenon like ecological succession if they can relate it to something they are already familiar with. To start this lesson, students will use the two photographs they’ve brought to class as an entry point to the topic of change over time. Tell students to place their photographs on their desks and take some time to look at them. Ask: “What do you notice about the two photographs? What has changed?” Collect ideas. String together common elements from the discussion and write them down so everyone can see.


Ask, “How do you know if changes are happening?” Explain that changes that take place over long periods of time are difficult to detect. We need to look closer at underlying processes in order to know that changes are happening. If we only look at snapshots of primary and end states (“snapshot reasoning”), we ignore the often-invisible processes that are responsible for change.

Gather students’ thoughts about how we understand changes over long periods of time. The students might, in this example, imagine that slow processes like bone growth or muscle build are responsible for the changes they see in their faces and bodies. Note: Depending on the age group of your students, you might want to focus only on facial change if the topics of puberty or adolescence will be sensitive or distracting.

Step 2: Transition to “Thinking Down the Line”
Introduce students to a thinking strategy called “thinking down the line.” In this strategy, students are asked to consider the intermediate states of something (a face, a plant, an ecosystem) as it changes over time. Ask, “What might your face look like ‘down the line?’ What factors might affect the way you eventually look?”


The RECAST simulation activity will shift the focus from the students’ appearance to the composition of ecosystems. It will also scaffold the task of considering intermediate states by displaying them visually and demonstrating the connection to changing underlying processes. It will, in other words, demonstrate the difference between “snapshot” and “video” reasoning about time and also reveal non-obvious causes.

RECAST Thinking


Step 3: Explain the Simulation Activity
The simulation is an interactive time-lapse animation that allows students to manipulate five environmental variables and play out the effects over time. Tell your students that they are going to be working with a software program about ecosystems and answering questions on an accompanying worksheet. Remind them to keep thinking about how changes happen over time and to connect with the idea of “thinking down the line.”


Note: If this lesson is part of the “Design Your Own National Park” unit, also remind your students to consider how this simulation might inform the design of their own National Parks.

Step 4: Experience the Simulation
Direct students to the online simulation. (For this lesson plan, the simulation is a series of images and examples of what might be expected from the final, programmed version). Hand out printed copies of the accompanying worksheet for students to fill out as they go through the simulation.


Ask your students to pay careful attention to how even the smallest changes to the ecosystem - temperature and precipitation, the presence of certain animal or plant species, or the fertility of the soil - can have large effects over time. Explain that succession is, like the changes we see in our appearance over time, the result of barely detectable underlying processes that are captured better by “video” (seeing the time-lapse animation play out) than “snapshot” reasoning (looking at photographs or end states).

Explore Causality


Step 5: Steady States Make it Hard to See Causal Patterns
Discuss with your students the differences between “snapshot” and “video” reasoning and highlight the important advantages and disadvantages to both. Make sure students understand that we typically use snapshot reasoning to understand long-term changes and often forget about the underlying processes evident in video reasoning. Ask, “What were you able to see in the simulation videos that you wouldn’t otherwise be able to notice?” Draw out key ideas from this discussion and write them down for the students to see.

Step 6: Non-Obvious Causes also Make it Hard to See Causal Patterns
It is also important that students observe the connection between manipulating environmental variables and long-term changes to ecosystems. Prompt students to share about their experiences with the simulation. Ask, “What happened when you changed a variable in the ecosystem and then looked at that ecosystem ‘down the line?’ Why do you think this happened?” Here are some examples of responses that will indicate students are thinking about the underlying causality of ecological succession:


  • “When I left all of the factors the same, the ecosystem looked pretty much the same after 50 and 100 years down the line, only with more trees. This is probably because the trees made more trees and the ecosystem had the right conditions for them to grow.”
  • “When I changed the climate by increasing the temperature and decreasing the precipitation, the ecosystem looked very different 100 years down the line. After looking at the time-lapse animation, I could see that the dryness changed the types of plants and animals that could live there, which made the entire ecosystem different.”
  • “It was interesting. When I removed the bears from the ecosystem it didn’t change very much at all 100 years down the line - there were just more trees and a few different types of plants. But when I removed the earthworms the entire ecosystem changed! There were very few plants and barely any animals. I think this is because earthworms are important for putting nutrients in the soil, which makes plants grow, which animals eat, and so on."

If your discussion about the simulation produces responses like these, it is likely that your students have gained a strong understanding of how changes play out in an ecosystem over time. If not, explain again how small changes related to the ecosystem’s balance can contribute to succession just like large changes (such as oil spills or forest fires) can.

Review, Extend, Apply


Step 7: Review Understanding Goals
Review the understanding goals for this lesson to give students the opportunity to be reflective about what they have just learned or are in the process of learning.


Step 8: Extend the Concept
Students started this lesson by connecting backward to their own experience in appearance change; they will finish by connecting forward to their own experience once more, this time in the form of different ecosystems they will encounter. First, ask students to imagine an ecosystem that they have seen change over the years. This can be any ecosystem, from a state park to a park down the street. For some students, this may be an urban ecosystem (loosely defined) like a playground or a city block. Ask, “How has this ecosystem changed over time? What intermediate states were involved? How might this ecosystem look 'down the line?'” Prompt students to imagine a time-lapse video of their ecosystem changing over the years. Loop back to how different this type of reasoning is from the connect backward, "snapshot" exercise at the beginning of the lesson.


Note: If this lesson is part of the “Design Your Own National Park” unit, apply this connect forward exercise to the students’ projects. Ask: “What might your ecosystem look like ‘down the line?’” Have students use video reasoning to play this out.