Objectives: Kids will learn why it is important for animals be adapted to their environment, including blending in, and how this adaptation works. They will complete an activity in which they are the predator, and must pick out the prey that stands out the most from its background.
Materials: Skittles (or colored beads), colored construction paper, Tupperware containers, plastic cups
Hello! Do you like Skittles? Did you know that they can be used to demonstrate a couple very important ideas of science?
Today we’re using Skittles to demonstrate the ideas of adaptation and natural selection. These are two very important things that occur in nature that have to do with how animals and plants change over time to fit in better with their surroundings and survive.
Have any of you heard of adaptation or natural selection? Do you want to try to explain what these terms mean?
[Give them a chance to define the terms, and give them feedback.]
A good way to start is by looking at this picture [show picture of polar bear in desert]. Do you notice anything unusual? What is wrong with this picture?
[Responses will probably be about how polar bears live in the snow, not the desert. Explore this a little bit, and ask them why.]
Why might a polar bear not do very well in the desert?
[First responses will probably be because they have fur and the desert is hot. Explore this a little with them. If they don’t mention coloration, bring this up…]
Another reason polar bears might not do well in the desert has to do with their color. We already talked about how they live in the snow. What happens to a white polar bear in the snow? Is it easy to see or hard? Now compare that to a polar bear here in the desert. Why is this important?
[Hopefully they’ll respond that it has to do with predatory advantages. If not, lead them with the following…]
How does a polar bear get his food? Does he go to McDonalds and buy a hamburger? [Pause for response] No, he has to hunt for it. A polar bear is what we call a predator. [Hold up predator/prey definition picture]. A predator is a hunter and the animals he hunts are called the prey.
Now, if you’re a predator, do you think it is better to blend in with your background, like a polar bear in the snow, or stand out from your background, like a polar bear in the desert? [Wait for response]
That’s right! If you blend in with your background, it is much easier to sneak up on your prey without them seeing you. And, if you’re prey do you want to blend in with your background or stand out? [Wait for response] You want to blend in, because it is harder for the predator to see you.
This is an example of natural selection. If you have advantages as either a predator or prey, you are selected, or chosen by nature to have a better chance to survive.
We’re going to demonstrate that now. Can I get a few of you to help me?
- Place the three containers in front of them. One container has yellow paper lining the bottom, one has green and one has purple.
- Explain that the yellow container is the desert (yellow sand), the green container is the jungle and the purple is the ocean. (Explain that you know the ocean is not really purple, but there are no blue Skittles, so they have to use their imagination and pretend there is a purple ocean somewhere…)
- Give them each a cup with some Skittles. Tell them the Skittles represent animals. Just as animals come in different colors (or people have different hair color, for example), the Skittle-animals are found in all different colors.
- Have them “populate” their environment (desert, jungle or ocean) by dumping all the Skittles in.
- Tell them that as the predator, they need to go hunting for food. Ask them to hunt by picking up the Skittles, one by one, selecting the ones that stand out and are easiest to see (just as a real predator would do in the wild).
- After they’ve selected all the ones that stand out, stop the hunting. Ask them to describe what is left. (It should be only Skittles that blend in with the background.)
- Explore their answers and discuss how blending in with the background gives them an advantage and allows them to survive.
Just like animals in the wild reproduce, or have babies, our Skittle-animals can have babies. What color offspring do you think the yellow Skittle-animals are likely to have? [Pause for response…they will probably say “yellow”]
That’s right…animals generally produce offspring that look like themselves. Polar bear cubs are white. Panda bear cubs are black and white. And yellow Skittle-animals are likely to have yellow babies. [At this point you can throw a few more yellow Skittles in the container to represent offspring.]
Over time, even if you start out with Skittles of all different colors, they are mostly going to look like this. [Point to containers which contain Skittles all of the same color]. That is what we mean by adaptation – a gradual change of a population over time to fit in better with its surroundings.
Every now and then, though, animals might produce offspring that look slightly different. [Toss in a couple Skittles that are different colors].
What do you think is likely to happen to these babies? [Pause for answer…they will probably give the correct answer, which is that they will be more likely to be eaten by predators]
These are the basic ideas of adaptation and natural selection. Do you have any questions?
If they are still interested, you can explore DNA and the nature of inheritance, i.e., why offspring generally look similar to their parents. You can extend this by talking about how DNA can mutate, causing changes (like yellow Skittle-parents having green Skittle-babies) and how these mutations are random.
Also, while some random mutations are bad (e.g., they make you stand out so you are more likely to be eaten by a predator), some are good, or advantageous and those animals survive even better, passing on their mutations and leading to further adaptation and natural selection.
Finally, for a cool example of adaptation, you can show the picture of the great white shark. Ask them to speculate on why they are white on the bottom, given that it is better for a predator to blend in with its environment. If they don’t get the answer (which they are likely not to get), ask them to think about what a small fish (prey) would see if they looked up towards the surface from below (it is brighter because they’re looking up towards the sun, so white things blend in).
Post-activity discussion questions:
- Why is it good for an animal to blend in with its environment? Why for predators? What about prey?
- How do animals come to be so well adapted to their environments?
- (if they have done Module 1 on genetics and inheritance) Do you remember genes and inheritance from last time? Why do you think it is important for genes to be inherited in this example?