Naturally, I Select You: Tactile Modeling of Natural Selection in the Classroom

I. Engage

Place squares of different colored paper (or just white) at each table and ask students to pick one, write their name on one side, and then hide their paper. The rules are it has to stay in the room and be in plain sight (you can't hide it in a book or bag etc). Tell students that any papers that remain hidden from you for the entire class period AND follow the rules of plain sight will earn a reward (extra credit, sticker, bragging rights, etc). Give them a couple of minutes to hide their paper then ask them to sit while you search for as many as you can find. Announce where you find them and the color of the hiding place and paper. Ask students if they notice any patterns (there may or may not be). Ask if anyone used a strategy and have them explain. Someone will probably mention camouflage. 

Tell students you have the rest of the class period to find the others so you hope they are masters of camouflage and you will show them one of the true masters-- the octopus. Show Video 1 Video 2 to the class.

II. Explore 

Remind students that the octopus is a rare example. Most animals don't have the option to change their appearance to match the environment. That is a special adaptation that just a few animals have. In our next game, we are going to model what happens to populations of frogs in different environments. (Don't forget to keep an eye out for their hidden papers while you narrate the story!)

Give students a copy of the log sheet (one per student or cooperative learning group), you can assign environments or let them pick, and have containers of model frogs ready (4 each of 5 different colors with others behind the scenes with you for mutations).

Start the game!

III. Explain

By the end of the game, students should have a pretty strong understanding of how the environment shapes a population and how mutations can change a population. What will not be very clear yet is the connection to genetics. Before going into explanations, you may want to use the attached "natural selection formative assessment probe" to see how much students understand and can explain.

Debrief the simulation with students giving them vocabulary words like natural selection and evolution, while explaining in more detail about the mutations. Make sure students compare their original populations to what they ended up with and note the differences in different environments. They have observed this frog population for 10 generations-- really even small changes take hundreds or thousands of years to change a population and form a new species, but this is a good model for how it starts.

IV. Elaborate 

There are a number of free simulations online that allow students to manipulate populations based on environment, resources, animal physiology, predators, etc. With the basic understanding built so far in this lesson, these simulations can help students master the concept. Sepup has a good one and a good student worksheet to go with it; PHET out of University of Colorado Boulder although it requires a download so if you have devices that require admin permission to download you will need to do that in advance.

An interesting historic example of natural selection is silica in grass. It is thought that grasses that took up some silica from their environments were defended against herbivores. Herbivores evolved their own mechanisms to digest the grass so grasses with more silica survived and reproduced, etc. 

Evolution is not always a biological race but sometimes that's a good analogy. You could also talk to students about the evolution of weapons and armor. That is human driven but it is the same idea. As our defenses change, our attacks change which means the defenses must upgrade and so on.

V. Evaluate

There is a formative assessment probe attached and student logs can be assessed for data collection, analysis, representation, and reasoned answers. 

I. Engage

Place squares of different colored paper (or just white) at each table and ask students to pick one, write their name on one side, and then hide their paper. The rules are it has to stay in the room and be in plain sight (you can't hide it in a book or bag etc). Tell students that any papers that remain hidden from you for the entire class period AND follow the rules of plain sight will earn a reward (extra credit, sticker, bragging rights, etc). Give them a couple of minutes to hide their paper then ask them to sit while you search for as many as you can find. Announce where you find them and the color of the hiding place and paper. Ask students if they notice any patterns (there may or may not be). Ask if anyone used a strategy and have them explain. Someone will probably mention camouflage. 

Tell students you have the rest of the class period to find the others so you hope they are masters of camouflage and you will show them one of the true masters-- the octopus. Show Video 1 Video 2 to the class.

II. Explore 

Remind students that the octopus is a rare example. Most animals don't have the option to change their appearance to match the environment. That is a special adaptation that just a few animals have. In our next game, we are going to model what happens to populations of frogs in different environments. (Don't forget to keep an eye out for their hidden papers while you narrate the story!)

Give students a copy of the log sheet (one per student or cooperative learning group), you can assign environments or let them pick, and have containers of model frogs ready (4 each of 5 different colors with others behind the scenes with you for mutations).

Start the game!

III. Explain

By the end of the game, students should have a pretty strong understanding of how the environment shapes a population and how mutations can change a population. What will not be very clear yet is the connection to genetics. Before going into explanations, you may want to use the attached "natural selection formative assessment probe" to see how much students understand and can explain.

Debrief the simulation with students giving them vocabulary words like natural selection and evolution, while explaining in more detail about the mutations. Make sure students compare their original populations to what they ended up with and note the differences in different environments. They have observed this frog population for 10 generations-- really even small changes take hundreds or thousands of years to change a population and form a new species, but this is a good model for how it starts.

IV. Elaborate 

There are a number of free simulations online that allow students to manipulate populations based on environment, resources, animal physiology, predators, etc. With the basic understanding built so far in this lesson, these simulations can help students master the concept. Sepup has a good one and a good student worksheet to go with it; PHET out of University of Colorado Boulder although it requires a download so if you have devices that require admin permission to download you will need to do that in advance.

An interesting historic example of natural selection is silica in grass. It is thought that grasses that took up some silica from their environments were defended against herbivores. Herbivores evolved their own mechanisms to digest the grass so grasses with more silica survived and reproduced, etc. 

Evolution is not always a biological race but sometimes that's a good analogy. You could also talk to students about the evolution of weapons and armor. That is human driven but it is the same idea. As our defenses change, our attacks change which means the defenses must upgrade and so on.

V. Evaluate

There is a formative assessment probe attached and student logs can be assessed for data collection, analysis, representation, and reasoned answers.