Biology Lesson
Survival of the Fittest: Unpacking Natural Selection
Shared by A STEM Educator★ Featured Teacher · rated 90+ in our quality review
7thBTC Style / Thinking Classrooms40 min
Learning Objective
Students will be able to explain how natural selection acts on heritable variation to change the frequency of traits in a population over time.
Lesson Overview
Students move from identifying basic survival advantages to explaining how traits spread through a population over generations, using whiteboard reasoning tasks that build one variable at a time.
Materials
- Vertical whiteboards or large chart paper
- Dry-erase markers (multiple colors)
- Pencils and paper
Scaffolded Task Progression
1Task 1
A field has two types of mice: tan mice and white mice. The field is covered in tan-colored dry grass.
1. Which mouse color is harder for a hawk to spot?
2. Which mice are more likely to survive and have offspring?
3. After many generations, predict: will the population have MORE tan mice, MORE white mice, or EQUAL numbers? Explain your reasoning on the board.
1. Which mouse color is harder for a hawk to spot?
2. Which mice are more likely to survive and have offspring?
3. After many generations, predict: will the population have MORE tan mice, MORE white mice, or EQUAL numbers? Explain your reasoning on the board.
2Task 2
Same field, same tan mice and white mice. Now the farmer plants WHITE SNOW CLOVER across the entire field — the field turns white.
1. Which mouse color now has the survival advantage?
2. Predict what happens to the population of tan mice over many generations.
3. Did the mice CHANGE COLOR to survive, or did something else happen? Explain.
(Hint: no new mice arrived — only the existing mice and their offspring.)
1. Which mouse color now has the survival advantage?
2. Predict what happens to the population of tan mice over many generations.
3. Did the mice CHANGE COLOR to survive, or did something else happen? Explain.
(Hint: no new mice arrived — only the existing mice and their offspring.)
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