Teachers TryScience

Classroom Setup

The setup of the classroom is flexible and up to the teacher, but one option is to have students work in pairs at their desks, and set up one area in the center of the table with a number of “food sources” for the tests. Ensure that the food sources are located relatively equidistant to where the students are sitting.

Introduction

1. Review with students Darwin’s observations on the beaks of finches in the Galapagos Islands.
2. Explain that today we will be conducting a simulation of the finches that Darwin studied on the Galapagos Islands.

Part 1: Competition for Resources

1. For the first part of the lesson, give each pair of students a plastic fork and a plastic cup. Inform them the fork will be their model beak and the cup is their nest. Their goal is to go to the food sources and bring as much food back to their nest as possible.
2. Place a large bowl of gummy worms at the center table for the food source.
3. One student from each pair will have one minute to bring as many gummy worms as possible from the food source to their nests.
4. Then the other student from the pair will perform the same activity.
5. Students average their two trials.
6. Inform students that all birds that have procured at least _____ gummy worms survive, while the rest are dead. (Perform this activity ahead of time and decide on an appropriate number such that most groups will survive)
7. Ask students to reflect on the results of Part 1.

• How many birds survived?
• How good was the fork at picking up the gummy worms?
• If some birds died, why do you think that was the case?

Part 2: Changing Environment

1. Inform the students that hurricane winds (or another form of natural disaster) have forced the finch population to another island where their original food was no longer available. They therefore have to resort to a secondary food source.
2. Place a large bowl of large seeds (make sure the seeds are too hard to be pierced by the fork) at the center table for the food source.
3. Repeat the same feeding procedures as from Part 1.
4. Inform students that all birds that have procured at least _____ seeds survive, while the rest are dead. (Again, perform this activity ahead of time and decide on an appropriate number, but this time make sure the number is difficult to reach).
5. Ask students to reflect on the results of Part 2.

• How many birds survived?
• Why do you think most of the birds died?
• Is this a realistic situation?

Part 3: Introducing Genetic Variation

1. Inform the students that we are going to “rewind” back to the original island.
2. Provide students with construction paper, scissors, tape, etc. and tell them they are allowed to modify their beak. Set constraints such as size limits (must fit inside a small box) and tell students they must leave the points of the fork exposed (so that it is still effective at picking up the original food source) but encourage them to be creative. The goal is to have many different beaks at the end of this section.
3. Ask students to reflect on their design.

• How did you come up with your beak?
• Do you think you will survive on both islands?

Part 4: Observing Natural Selection

1. Repeat Part 1. Students that designed their beaks according to the constraints should still survive. The other students that die do not move on to Part 2.
2. Repeat Part 2. With the newly designed beaks, hopefully some students were able to successfully design beaks that allowed them to survive. You may repeat this part more than once, making the criteria harder each time until only a couple of beaks survive.
3. Ask students to reflect on the results of Part 4.

• How many birds survived this time?
• Why do you think this was the case?
• Is this a realistic scenario?