Shape Shifters

DON'T SPOIL THE SURPRISE! Without knowing that they’re participating in a natural selection simulation, students build stacks of colored shapes and submit them to a “judge.” A big reveal at the end lets them in on what’s really been going on.

This activity is designed to create productive uncertainty in students. It should become a springboard for discussion and a tool to shift student thinking (or disrupt their preexisting ideas about Natural Selection).

As such, it is intentionally vague at the beginning; it will become clear to students in the end. Randomly designing shape stacks mimics random genetic variation, and the “judge” is the non-random process of natural selection. This is hidden from students in the beginning to underscore the point that natural selection is not a goal-directed process – it just happens.

To connect the shape stacks to alleles, you can think of each position in the shape stack as a gene and each shape/color combination as an allele. Be sure that students understand that in reality, it takes far more than 3 genes to make a butterfly wing pattern.

Have students explore individually or in pairs.

Optional: Create a competition where students try to figure out what the “judge” is. Early in the simulation, have them write their answers on sticky notes and place in a central area.

Discuss one or more of the questions below as a whole class, or have students reflect on one or more of the questions in small groups or individually. Record their thoughts (or not) according to your preference.

Have students play through the simulation a second time.

• Individuals that reproduce successfully pass their genes, and the resulting traits, to the next generation.
• Individuals with traits that favor survival are more likely to have offspring.
• As traits that favor survival are passed down through generations, those traits become more common.

Student devices with internet access

Shape Shifters

• In real life, what is the judge? (the environment)
• Why did the judge reject the ones it did? (they were eaten by predators)
• What did it mean to pass (be accepted by the judges)?
• Did you end up with butterflies that didn’t look as expected? Why do you think that happened? (Natural selection can only work with available variations, not make new ones. Helpful variations may have been randomly eliminated from the gene pool in the earliest round, or they may not have been there in the first place.)
• What is mimicry?

• “I made a supporting worksheet for Shape Shifters using the discussion questions and told them to find the answers at the end when it started explaining things. This helped my students to better pay attention to the why behind the activity. When most of them were finished, I quickly got to the end of the simulation and read over the explanations while discussing the answers to the questions, which helped pull in the students who don't read/understand as well.”
• “I think that it would be interesting if you could develop a less dramatic version of the Stephen Hawking experiment. I would love to have teams of students, half in the classroom and half in the lab, who were working blindly with each other…Perhaps make shapes with a substance and have the tester determine which could float and which would sink in water, or which could be rolled down a table towards a target. I think that this could bring home the concept of random mutations occurring and of unknown environmental conditions in which the mutated traits might be helpful. The Shape Shifters simulation is interesting, but a hands-on activity would be much more powerful.”

Consider following this activity with one of the following videos:

• It's Okay To Be Smart video about mimicry (5:20)
• Evolution clip from Genius by Stephen Hawking (10:30)