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3rd grade · Science · Unit 4 of 8

Speed & Motion

Fast and slow, why things keep moving, and what changes how quickly motion changes.

What your child practices

Practices speed as the distance an object travels in a certain time, inertia (objects keep doing what they are doing until a force acts), and how mass and force affect how quickly motion changes.

Alaska content standards learning standard: 3-PS2-1; 3-PS2-2 · how forces change motion and patterns that predict motion

How we explain it

Children can open this short lesson before they practice.

  1. Speed is how far something travels in a certain time.
  2. Things keep doing what they are doing until a force acts on them.
  3. Friction slows things down. Rough grass has more friction than smooth ice.

Example: A runner goes 10 km in one hour. A walker goes 5 km. Who is faster? Both took one hour. 10 km is farther than 5 km. Answer: the runner

Speed & Motion in Alaska

In the Alaska content standards, this is unit 4 of 8 in 3rd grade Science, after Basic Needs & Life Cycles and before Traits & Variation.

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

    Which unit could measure the time something takes?

    • liters
    • seconds
    • meters

  2. Question 2

    Which surface has the most friction?

    • Wet glass
    • Rough carpet
    • Smooth ice

  3. Question 3

    A heavier shopping cart needs a ___ push to start moving than a light one.

    • smaller
    • no
    • bigger

  4. Question 4

    An object at rest stays at rest unless…

    • it is tired
    • a force acts on it
    • it gets hungry

  5. Question 5

    You are in a car that suddenly stops. Your body leans forward because of…

    • inertia
    • hunger
    • cold weather

  6. Question 6

    Runner A goes 100 m in 20 s. Runner B goes 100 m in 25 s. Who is faster?

    • Runner A
    • Same
    • Runner B

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