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9th grade · Science · Unit 16 of 28

Populations & Evolution

Population math, group behavior and how environments change species.

What your child practices

Practices using numbers to describe populations and biodiversity, judging the evidence that group behavior such as packs, schools and herds helps animals survive, using proportions to explain how a helpful inherited trait spreads, and how environmental change can grow some populations, form new species and end others.

New York State Learning Standards learning standard: HS-LS2-2; HS-LS2-8; HS-LS4-3; HS-LS4-5 · population numbers and biodiversity, group behavior and survival, how helpful traits spread, and how environmental change leads to new and extinct species

How we explain it

Children can open this short lesson before they practice.

  1. Use percentages to describe population change: find the percent, then add or subtract it.
  2. Group behavior, like packs, schools and lookouts, helps animals survive.
  3. A helpful trait becomes a bigger proportion of a population over generations.

Example: A population of 200 deer falls by 10%. How many are left? 10% of 200 is 20. 200 − 20 = 180. Answer: 180

Populations & Evolution in New York

In the New York State Learning Standards, this is unit 16 of 28 in 9th grade Science, after DNA, Proteins & Traits and before Plate Tectonics.

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: New York State Education Department (NYSED)

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

    When its environment changes, a species may…

    • stop needing food
    • always stay exactly the same
    • adapt, move away or go extinct
    • turn into a rock

  2. Question 2

    A population of 400 frogs falls by 25%. How many frogs are left?

    • 300
    • 425
    • 100
    • 375

  3. Question 3

    Mammoths and mastodons died out not long after the end of the…

    • Roman Empire
    • 1800s
    • Middle Ages
    • last Ice Age

  4. Question 4

    Wolves hunting in packs can catch large prey like elk. This group behavior helps each wolf…

    • become a new species
    • avoid all other wolves
    • get more food than it could alone
    • stop eating

  5. Question 5

    A new species can form when a population is…

    • moved to a zoo for a week
    • separated and changes over many generations
    • given more food for one day
    • counted by scientists

  6. Question 6

    Zebras in a herd are harder for lions to catch because…

    • many eyes watch for danger and stripes blur together
    • lions avoid all herds
    • zebras are invisible
    • herds have no predators

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