ALEX Lesson Plan

In terms of life science content, evolution is essentially where genetics meets ecology. In this introduction to evolution, students will take on the role of both research biologists and predators to simulate how environmental conditions affect and change a population of model frogs and traits. Students will encounter the impacts of mutations and changes to the environment affecting the survival as well.

This lesson results from a collaboration between the Alabama State Department of Education and ASTA.

NOTE: The specific colors and materials don't really matter-- whatever works for you and/or is cheap and available will be acceptable

You will need:

2 different "habitats"- these need to be multicolored and fit on a table/desk depending on available space in your classroom. Tablecloths, fabric, and wrapping paper are all great options. Try to have two different color schemes with multiple but not all colors. Ex, if you have a hot pink environment counter that with a green or blue environment. Avoid metallics.

Model frogs- have about 8 colors, make sure a couple colors will camouflage well with each habitat, plus a couple random ones (one metallic; you could use ribbon, a sheet of metallic paper from a craft store, or foil). Paper is the easiest option but you can use anything. Hole punch, cut squares, etc.

Optional: Colored Pencils

Student Worksheets (attached): one per student or group

Teacher Script: Attached 

Projection equipment

Access to internet or download videos 

Evolution is where genetics and ecology meet. The better suited an individual is to its environment, the more likely it is to reproduce and pass on the genes it had that made it fit to live and survive in that environment. Genetic mutations are rare but occur naturally. Sometimes they are favorable, sometimes neutral, sometimes unfavorable. Bacteria are a great way to illustrate this because they have such quick cycles of reproduction and mutation. However, for 7th grade it is still an abstract concept, so a tangible simulation like this game will engage students while highlighting some of the key concepts for them to learn. Feel free to adjust numbers in the script to suit your own class size. 

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. 

Formative assessment probe, answers during group discussions, log, data to determine if the learning targets are met.

• I can explain how evolution is driven by environmental factors and natural selection.
• I can connect that the changes to individuals in a population are linked to their own genes and those that they pass to their offspring.
• I can differentiate between a single mutation and a long-term change in a population. 

If you have already taught genetics a good summative assessment would involve the link between genetic transfer and mutation and natural selection/evolution. 

Evolution is a sensitive subject for some students. This is a very non-threatening approach but you may want to do some kind of discussion before hand about it. You can ask students to write anonymously what they think or feel about evolution the day before so that you know their feelings going into it. Or you can explain that, as with everything in science, this is a theory, an idea. It is supported by evidence, some of which we will model today, but it is an attempt to figure out how the world works, not challenge anyone's deeply held beliefs.