Instructional Material · 8.MS-LS4-4

Natural Selection: The Survival Game

A 25-minute Grade 7–8 demo lesson using the peppered moth as a data-driven survival game to explain how variation, selective pressure, and differential survival shift populations over generations.

MA STE 8.MS-LS4-4 Population Change Data Interpretation Misconception Correction DOK 1–4 Causal Reasoning

Lesson Aim & Essential Question

Aim

Students use evidence from trait variation and population data to explain how natural selection causes populations to change over time.

Essential Question

If two individuals of the same species look different, does that difference matter — and to whom?

The Four-Step Framework

1. Variation

Individuals in the same population have inherited differences, such as light and dark wing color.

2. Selective Pressure

The environment determines which traits are advantageous; in this case, bird predation and bark color.

3. Differential Survival

Better-camouflaged moths survive longer and reproduce more often.

4. Population Change

Over many generations, advantageous inherited traits become more common in the population.

Visual Model: Same Predator, Different Environment

This graphic supports the lesson’s core misconception correction: individual moths do not choose to change color. The population changes because different individuals survive and reproduce under different environmental conditions.

Population Data

Instructional Sequence

Hook · 3 min“You are a hungry bird. Which moth do you eat first, and why?”

I Do · 8 minTeacher models the four-step framework and corrects the “individuals change” misconception.

We Do · 8 minThink-pair-share: predict the effect of clean air laws using the causal sentence frame.

You Do · 6 minWorksheet completion and exit ticket, collected at the door.

Language Frame

Because the environment changed to ______, the ______ trait became more advantageous. This means individuals with ______ wings were more likely to survive and reproduce, which over time caused the ______ population to ______ because ______.

Assessment Architecture

Component	Skill Checked	Evidence of Mastery
Worksheet	Data interpretation, variation, selective pressure, and population change.	Students explain the peppered moth trend using evidence rather than choice-based or individual-change misconceptions.
Exit Ticket	Individual mastery of variation, industrial-era selection, and post-clean-air prediction.	Students identify variation correctly and predict that light moths recover when pale bark returns.
Progress Check	Teacher-facing formative tracking across DOK levels.	Checklist records variation, selective pressure, differential survival, graph interpretation, sentence-frame use, and misconceptions observed.
DOK Extension	Transfer to new contexts.	Students map variation → selective pressure → differential survival → population change to antibiotic resistance or a new environmental scenario.

Misconceptions Explicitly Addressed

Individuals do not evolve

Individual moths do not change color during life; populations shift across generations.

Fitness is contextual

Fitness means reproductive success in a specific environment, not strength or size.

Environment changes advantage

The same trait can be beneficial or harmful depending on bark color and predator visibility.