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4th grade · Science · Unit 8 of 8

Rock Layers & Erosion

Weathering, erosion and what rock layers tell us.

What your child practices

Practices how water, ice, wind and plants break down and move rock, and how patterns in rock layers and fossils show how a landscape changed over time.

Alaska content standards learning standard: 4-ESS1-1; 4-ESS2-1 · rock layers and fossils show landscape change, and weathering and erosion shape the land

How we explain it

Children can open this short lesson before they practice.

  1. Weathering breaks rock. Erosion moves it. Running water moves the most.
  2. Glaciers scrape and carry rock. Roots growing in cracks can split rock.
  3. Over a very long time, erosion can carve deep canyons.
  4. Plants and their roots slow erosion on a hillside.

Example: Which hillside erodes faster in heavy rain: a bare one or a grassy one? Roots hold soil in place. A bare hill has nothing to hold the soil. Answer: the bare hillside

Rock Layers & Erosion in Alaska

In the Alaska content standards, this is unit 8 of 8 in 4th grade Science, after Waves & Codes.

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: Alaska Department of Education and Early Development

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

    A glacier moving down a valley…

    • makes the valley taller
    • scrapes and carries rock
    • builds volcanoes
    • stops erosion

  2. Question 2

    Sand dunes are shaped by…

    • glaciers
    • wind
    • lava
    • earthquakes

  3. Question 3

    Rounded river rocks got smooth because…

    • they melted
    • they were painted
    • wind sanded them in a day
    • water tumbled them

  4. Question 4

    A river carved the Grand Canyon by…

    • one big flood in a day
    • wind only
    • erosion over a very long time
    • an earthquake

  5. Question 5

    Plant roots growing in cracks can…

    • make rock
    • break rock apart
    • glue rock together
    • melt rock

  6. Question 6

    In a stream table test, more water flow causes…

    • no change
    • more erosion
    • less erosion
    • rock to grow

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