Series Ecosystems: An NGSS-Designed Unit : Ecological Interactions

Ecological Interactions

Lesson Objective: Determine how the reintroduction of wolves affected a food web
Grades 6-8 / Science / NGSS
10 MIN


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Discussion and Supporting Materials

Thought starters

  1. How do students engage in exploration through this activity?
  2. What do students learn from making their own food webs?
  3. How does making food webs prepare students for analyzing the reintroduction of wolves?


  • Private message to Shay Centilli

I love how this teacher tells the students whenever theyre doing the dry erase markers that this is their trail and error and time to make the mistakes, because mistakes are ok just as long as we are eventually learning how to correct them, which these students seemed to catch on. 

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  • Private message to Ryan Cantrell

By the teacher creating this activity as a explore activity, allowed the children to do "trial-and error" with their food webs. As she taught the lesson on reintroductions, the students were able to see the areas they messed up on and the connections between the animals. She used this to show how the introduction of the wolves can change a food web instantly.

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External Resource Materials


  • Ecological Interactions Transcript

    Speaker 1: So today we're starting 1.2. The topic was ecological interactions. Our guiding question for one 1.2

    Ecological Interactions Transcript

    Speaker 1: So today we're starting 1.2. The topic was ecological interactions. Our guiding question for one 1.2 is what effect did the reintroduction of wolves have on the food web in Yellowstone National Park.

    Speaker 2: In this activity the students explore feeding relationships of the living things in Yellowstone National Park by developing their own food web amongst 12 organisms. They also start to speculate how humans have an impact on the food web and how the wolf reintroduction has impacted the food web as well.

    Speaker 1: Activity 1.2 is an explore activity where the students start learning about the relationships through the food web. Traditionally teachers explain before they explore, where they'll give kids the definitions and then show them examples. But in 1.2, because they're using this card set and exploring the food web in this way, they're figuring out the science concepts through the modeling that they're doing in 1.2.

    Students: So humans wiped out the wolves.

    Speaker 2: In the past activity the students learn about the wolf reintroduction, and now it leads into 1.2 where we explore the Yellowstone environment and how the wolf reintroduction will impact it.

    Speaker 1: After studying environment, scientists may observe patterns in a way that living things interact.

    Speaker 2: We learn about food chains and food webs as diagrams that scientists use to map out the interactions of living things in an environment.

    Speaker 1: So today you guys are going to get a set of 12 cards that represent 12 of the main living things in Yellowstone National Park.

    Speaker 2: We took those organisms and directly applied them to make food chains.

    Speaker 1: Group them according to similarities based upon your prior knowledge.

    When you are done, raise your hand and Miss [Dora 00:02:09] and I will come around and hear your explanation of how you decided to group those cards. Once we've heard you, you're gonna check off you got it done.

    Students: What would eat a tick?

    Students: Well, that's exactly-

    Students: I think it'd be right there. I think some of these animals may eat ticks.

    Students: Uh...

    Students: Ticks are nasty, I don't-

    Students: Tick or those?

    Students: [crosstalk 00:02:37] hard to teach.

    Students: Well, both of them work, so we could put it like this.

    Speaker 2: How did you move your cards?

    Students: So the prey would eat the plants and then the predator would eat the prey.

    Speaker 2: So it's kind of like a tiered level, right, a hierarchy?

    Students: Grizzly bears, they are mammals cuz mammals are basically anything that doesn't have eggs.

    Speaker 2: Okay.

    Students: These are all mammals.

    Speaker 2: Alright, so these are your three groups. And these are the ones that are-

    Students: Don't eat meat. Don't eat [crosstalk 00:03:09].

    Speaker 2: So they are herbivores. And what do you mean by herbivores?

    Students: They really eat plants and [inaudible 00:03:15].

    Speaker 2: Go ahead person number four, check off [inaudible 00:03:17].

    Students: Check off the first one.

    Students: Okay.

    Speaker 1: So tomorrow we are going to continue exploring the answer to this question of, what effect did the reintroduction of wolves have on the food web in Yellowstone National Park?

    Today we're continuing on and expanding our food chain into the food web that represents Yellowstone National Park.

    Speaker 2: In the next round of 1.2 the students get the 12 cards of organisms again.

    Speaker 1: I have these dry-erase neon markers that you guys will directly use arrows to connect one card to another if you know there's a feeding relationship.

    Speaker 2: The reason we use dry erase markers is it's supposed to be temporary, it's their initial food web.

    Speaker 1: Did anyone catch the year that this food web is from? Yeah?

    Students: 1990.

    Speaker 1: 1990. So that was before we reintroduced the wolf, right? So you'll notice you don't have a card that says, "The wolf" yet.

    Once you guys are all in agreement, or mostly in agreement, record what you have on your table, so you have your own record in your notebook.

    Students: Alright, so you ready to draw the arrows?

    Students: Yeah, on the table. Directly on the table.

    Students: We need space between-

    Students: Oh, my god.

    Students: This is awesome!

    Speaker 1: Make sure you spread out these cards cuz there has to be drawing space.

    Students: I don't think the grizzly bear [crosstalk 00:04:49]. It's gonna get eaten by the winter tick.

    Students: Winter ticks don't kill. They only take blood, make babies, and then-

    Students: Oh my god.

    Students: -and you know, reproduce, and then-

    Students: Elk to coyote and deer, and then bison to grizzly.

    Students: Coyote to winter tick, grizzly to [crosstalk 00:05:14].

    Students: Can a grizzly eat a coyote?

    Students: I think it probably could.

    Speaker 1: So could it happen, but what really happens? If you don't think it's really there-

    Students: It could happen but it mostly would not likely happen.

    Speaker 1: So let's remember, we're trying to represent the real relationships in Yellowstone.

    Students: Okay, they wouldn't.

    Speaker 2: Choose the team next to you, actually, choose this team. See how theirs is different than yours, and then go ahead report back to their team.

    After they went to visit another group and come back to make revisions of their food web, they got a new data sheet with new information about the diet about different living things in the Yellowstone National Park environment. With that sheet students got a new marker and started making revisions.

    Speaker 1: Switch your marker because we want to see when we look at your table the changes you made.

    Speaker 2: Based upon the new information the students, I think became overwhelmed with all the extra arrows that they were adding to the food web, they were shocked at all the connections just those 12 organisms had with each other.

    Students: Bison [inaudible 00:06:10] elk?

    Students: Yeah, the ticks eat the bison and the elk.

    Speaker 1: So let's pause, everyone should be sitting down now with your notebooks.

    Speaker 2: I went around the room and saw a lot of revisions.

    Speaker 1: Yeah, so share one change that you made. Brandon.

    Brandon: We put the winter tick eats pine seeds, but it doesn't, it eats blood from elk and bison.

    Speaker 2: Okay, so that was a common thing that I saw was the winter tick people had the wrong connections to the winter tick.

    Moving on now, the patterns of interactions. So which organisms play a similar role on this food web? Yes, go ahead Clara.

    Clara: A lot of animals ate the grasses.

    Speaker 2: Tell me two things that ate grass.

    Clara: Bison and elk.

    Speaker 2: Okay, bison and elk had a similar role. And one other? AJ.

    AJ: The grizzly bear and the coyote are both kind of at the top of the food chain.

    Speaker 2: Mm-hmm (affirmative).

    AJ: So they're both predators and they basically almost eat everything.

    Speaker 2: Okay.

    AJ: Let's take the grizzly bear for example. He eats nuts and berries, and on top of that he also eats mammals.

    Speaker 2: In the next part they finally get a gray wolf card introduced into their food web and see what connections they can make.

    Speaker 1: In 1995 that's when the gray wolf was introduced. On your information sheets that we give out, it has the diet of the wolf. Read it right now, and let's see where does this gray wolf fit in.

    Students: The gray wolf would not be able to eat the cowbird.

    Students: Yeah, it would. It says, "Large and small animals."

    Speaker 1: So what do wolves, gray wolves eat?

    Students: It's not likely for a gray wolf to eat a cowbird. [crosstalk 00:07:55].

    Students: But they could.

    Students: It could be if it sneaks up to one.

    Students: Yeah.

    Students: It's very unlikely.

    Students: Okay.

    Students: It's possible.

    Speaker 1: If you're not so sure, make a dotted line arrow to that thing, actually do it right in your notebook because you want it in your own copy.

    Speaker 2: So it's okay that they were struggling and being overwhelmed with all the arrows that they were creating in their food web because this is the first time that they are creating a food web of a real environment.

    Speaker 1: Look at the model. Look at your food web, and see if you can use the idea of cause and effect to tell me what effect you think adding the wolf did to the Yellowstone food web.

    Speaker 2: So to wrap up 1.2, we went back to the cross-cutting concept posters in the back of the classroom to add in the additional cross-cutting concept of cause and effect.

    Students: It took away the animals that, like, the coyote or grizzly bear were feeding off of. It made the food source, like it took away most of the animals.

    Speaker 1: Food source ... What's that word? Who can help out? He's trying to think of the word, so it made the food source, what? Yes, [Anya 00:09:07]?

    Students: Scarce?

    Students: Scarce for other animals to eat.

    Speaker 1: So this other example you're saying it's still about, by adding that wolf, your prediction, based on your model, is that it will eat the food from other animals, which might affect them. It might cause those other animals not to have food. So again that's how cause and effect might help us. At another point in time, we should revisit this and think about the cause and effect relationship with humans in the environment as well, because this morning in your [inaudible 00:09:37] you added humans, and that might also cause changes and so on in the food web that we'll want to think about.

    I feel like the students were in a really good place to start exploring that content and I do think that they did a good job figuring out those relationships so that when they get the terms in the next activity they'll be ready.

    Speaker 2: So this explorer phase leads into 1.3 where the students finally get to label the patterns and interactions that they saw within their food web.

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Lesson Idea
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