How Natural Selection Works
Explain natural selection as the mechanism of evolution: heritable variation + competition for resources + differential survival and reproduction = change in allele frequency over generations
Lesson
Set out your lesson
“Natural selection occurs when inherited differences affect survival and reproduction. Gene variants are alleles; changing their frequencies across generations is genetic evolution. Selection is one mechanism of evolution. Individuals do not turn into a needed type. Limited resources create competition, but a helpful trait never guarantees survival. Safety: No live insects, outdoor lights or predator feeding. Stop: Stop after one model generation and a reversed-background prediction. Do not capture moths or test predation.”
Bring to the table
- Paper
- Pencil
Extra for the adult
Worked example. The dark share changes from 2/10 to 6/10. Dark parents left more offspring in this supplied dark-background model. This is selection changing an inherited population trait, not eight light moths choosing to become dark. Counts were assigned for practice, not collected outdoors.
Optional challenge. Could a helpful inherited trait still be lost by chance in a small population? Explain why selection is not a guarantee. Adult key: Chance can remove a variant, especially in a small population, even when that variant has an average reproductive advantage.
What to notice. Keep the generation drawing and explanation. Note whether the adult supplied counts, labels or causal links; the outcome counts are provided support.
Share and support
Family records and proof options
Keep a record of your learning
Save photos, notes, and attendance. Export a proof packet for compliance or portfolio reviews.
Learning resources
Extra practice links — they do not replace Gakuva’s teaching approach.
PhET Interactive Simulations · Practice link — not the full lesson
Natural Selection
Before you open · source notes
Natural Selection supports hands-on exploration for How Natural Selection Works. Not every lab worksheet.
Free interactive page, no sign-in required for the tested path.
Before you openAsk the learner what they changed in the sim or page and what they observed.
Opening this link does not save learning or assess mastery.
Source, access and review notes
Public PhET Interactive Simulations page. An anonymous GET on 2026-11-12 returned HTTP 200 with no login or payment prompt for this URL. Opening the link does not save practice or assess mastery. An adult should preview and guide the learner.
PhET Interactive Simulations. “Natural Selection.” External page; Gakuva does not copy, host, embed, or redistribute materials.
Unknown — link only
Check understanding
- Describes the four conditions required for natural selection to operate (variation, heritability, competition, selection)
- Applies the concept to a specific example (e.g. antibiotic resistance in bacteria, peppered moth)
- Explains why individuals with advantageous traits leave more offspring
- Distinguishes natural selection from evolution (selection is the mechanism; evolution is the result over many generations)
“If your child heard about bacteria becoming resistant to antibiotics, could they explain how that happened using natural selection — without the bacteria ‘choosing’ to change?”
Curriculum record
- Type
- Conceptual
- Subject
- Science
- Domain
- Ecosystems & Habitats
- Age range
- Ages 12–14
Standards