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Science

Evolution by Natural Selection

Overview

Students explore Charles Darwin's central insight — that variation plus selection produces change over time — and apply it to real biological examples.

Learning Objective
Students understand how natural selection drives evolution and can apply the concept to explain observed changes in populations over time.

Resources needed

  • None

Lesson stages

0 / 7 done
  1. 1 Ask: why are no two individuals in a species identical? (Variation — from reproduction and mutation).
  2. 2 Introduce natural selection in four steps: variation exists, some variants are better suited to the environment, better-suited individuals survive and reproduce more, their traits are passed to offspring.
  3. 3 Apply to an example: the peppered moth — light moths on clean bark, dark moths on soot-covered bark after industrialisation.
  4. 4 Ask: did individual moths change colour? (No — the population changed because dark moths survived better).
  5. 5 Discuss: how does antibiotic resistance in bacteria illustrate natural selection at high speed?
  6. 6 Introduce Darwin: his observations during the voyage of the Beagle — finches in the Galápagos with differently shaped beaks.
  7. 7 Ask: what evidence do we have for evolution? (Fossils, DNA similarities, observed changes in populations).

Tap a step to mark it as done.

Variations

  • Simulate natural selection: students are predators, picking up coloured paper dots from grass — which colour survives longest?
  • Discuss artificial selection: how humans have selectively bred dogs, crops, and farm animals.
  • Examine the fossil record: what does it show about change over time?
More information

Teach: variation, selection, adapt, survive, reproduce, population, generation, evolve. A crucial distinction: evolution happens to populations over generations, not to individuals during their lifetime.

Focus on the four steps of natural selection with one clear example before discussing evidence or antibiotic resistance.

Can students explain the four steps of natural selection in the correct order? Can they apply the concept to a new example without prompting?

The peppered moth and antibiotic resistance examples require no materials. The simulation uses different coloured paper — very low cost.

Students very commonly believe that individual organisms evolve during their lifetime. Natural selection acts on populations across generations — individuals do not change to suit their environment.

Evolution by natural selection is the central unifying theory of biology.

Activity details
Secondary Challenging 25–30 minutes no prep Whole Class, Small Group Indoor & Outdoor
Topics
Evolution Natural Selection Genetics