Ecosystems Curriculum

Section 1: Resources

Picture of Practice

Learning About Extended Effects in an Ecosystem: 5th Grade Lesson on Domino Cause and Effect

In this lesson, fifth graders are exploring the relationship of organisms in an ecosystem. Through a classroom discussion following the Web of Life game, they discover that an ecosystem can be described as a food web and that cause and effect relationships extend beyond the notion of a food chain. Here we look in on some of that conversation.

Ms. Nolan shows the students some dominoes.

• Ms. Nolan: How many of you have played with dominoes before? Who can describe how they work?
• Becca: You set them up in a line so that one hits another and knocks it down, and that one hits another and another and another.
• Ms. Nolan: Okay (setting a few dominoes up and knocking them over to illustrate Becca’s idea) Now I want you to take some time to think about how these dominoes might be like the food web we created in the game. (She gives the students think time.) What do you think?
• Jake: It’s just like, if this falls down, like pretend it’s an animal that dies, then the other animal that eats it will fall down. Then that animal will die because it doesn't have that animal to eat.

Ms Nolan sets up a string of dominoes.

• Ms. Nolan: So, let’s pretend that this domino here is the green plants, and this one is the mice and this one the snakes. If the green plants die (Ms. Nolan knocks down the green plants), what happens to the mice and the snakes?
• Emma: They’ll die, too?
• Ms. Nolan: Yes, sometimes it might look more like this. (She sets up the dominoes to create a system that has two branches radiating from the green plants, and creates some connections from there.) Now, here are the green plants. Here are insects that eat green plants, but here are the mice that also eat green plants. And on this side are the toads that eat insects, and over here we have snakes that eat the mice. Now what will happen if the green plants fall?
• Carlos: They'll all fall.
• Ian: But they won't all fall because the toads could still eat insects. They don’t eat green plants.
• Olivia: Yeah, but the insects won’t be there because they need the plants.
• Ian: So the toad can eat dead insects.
• Jake: And once he eats them all up what will he do?
• Ms. Nolan: Well, let’s think about this. If we had the green plants but all of the insects disappeared, maybe the toad could find some other food to eat, as Ian is suggesting. Animals do sometimes change their diet. But remember that the green plants have a special name for their role. Can anyone remember what it was?
• Katie: Producers.
• Ms. Nolan: Right, because they are the only ones who can take the energy directly from the sun. So what does that mean?
• Jake: If they disappear, the other things will, too.
• Ms. Nolan: (demonstrating by knocking down the dominoes). Everything else would fall like dominoes. It might take a little while, but that's what would happen. Okay, earlier when we were using the cards and string to create our ecosystem, someone said this was like a spider's web. How is it like a web?
• Jake: Because when we connected all the things that ate each other with strings, it was all connected, like a web.
• Hannah: It's like a food chain.
• Ms. Nolan: Some people call it a food chain and some people call it a food web. How is it a food chain?
• Tyler: Because one thing eats another thing, right down the line like a chain.
• Ms. Nolan: Right. That's like I showed you in the first example where we had the green plants, mice and snakes. But calling this a food web is another way of thinking about this. A food web is like what I showed you in the second example where I had to put my dominoes in more than just one row, more like a web shape to show how knocking down the green plants wouldn't just knock down just the insects, but other things that eat green plants too. So a food chain is one good way to think about it, but a food web tells us more about how things are connected.

Ms. Nolan writes "Domino Cause and Effect" on the board.

• Ms. Nolan: People call this kind of food chain and food web "domino cause and effect". What do you think they mean by that? Let's start with cause. What's a cause?
• Jack: A cause is something that makes something happen.
• Ms. Nolan: Okay. And an effect?
• Jack: An effect is what happens.
• Ms. Nolan: Okay, an effect is the thing that happens because of the cause. So, a cause is the thing that makes something happen and an effect is the thing that happens. (Setting up two dominoes.) If I push this one and it makes the next one fall like this, this one is the cause that made it fall. Now if I set them up like this (setting up four dominoes) and I push this one down and they all fall, what would you say about the cause and effect?
• Emily: Well, the first one is the cause because it made the next one fall down. But then that one made the other one fall, and the other one. So those are causes too.
• Ms. Nolan: Right. This one made the next one fall, which made the next one fall, which made the next one fall. This is what we call "domino cause and effect." It's a good way of thinking about how the energy from the sun affects all of the things in the food web and what would happen if the green plants that make the link to the sun disappeared.