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9th grade · Science · Unit 8 of 10

Evolution & Selection

Variation, adaptation and how populations change over time.

What your child practices

Practices variation, adaptation, natural and artificial selection, mutations, the evidence for evolution from fossils and rock layers, and how new species can form.

Arizona Academic Standards learning standard: HS.L4U1.28; HS.L4U1.27 · natural selection and adaptation in populations

How we explain it

Children can open this short lesson before they practice.

  1. Variation and mutations give individuals different traits. Adaptations help them survive where they live.
  2. Natural selection lets well-suited individuals reproduce more; in artificial selection, people choose.
  3. Fossils and rock layers show life changed over time, starting with single-celled organisms.

Example: A cactus stores water in its thick stem. This is an adaptation to what? Storing water helps when rain is rare. Answer: dry climates

Evolution & Selection in Arizona

In the Arizona Academic Standards, this is unit 8 of 10 in 9th grade Science, after Chemical Change and before Energy & Magnetism.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Arizona Department of Education

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    Natural selection is when…

    • nature chooses on purpose
    • the strongest always win
    • individuals with helpful traits survive and reproduce more

  2. Question 2

    A selective pressure is…

    • a school rule
    • a type of fossil
    • an environmental factor that affects survival

  3. Question 3

    Sexual reproduction increases variation because…

    • offspring are clones
    • no genes are involved
    • offspring get a new mix of genes from two parents

  4. Question 4

    Which is an example of artificial selection?

    • a bird growing a longer beak by exercise
    • fish living in a cave
    • farmers breeding cows that give more milk

  5. Question 5

    A cactus's thick stem that stores water is an adaptation to…

    • cold lakes
    • dry climates
    • ocean tides

  6. Question 6

    Sexual selection is when…

    • animals avoid all mates
    • traits that help with digestion are lost
    • traits that help attract mates become more common

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