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4th grade · Science · Unit 7 of 8

Waves & Codes

Waves, amplitude, wavelength and sending patterns.

What your child practices

Practices how waves have amplitude and wavelength and can make objects move, and how patterns like codes, flashes and digital signals carry information.

Alaska content standards learning standard: 4-PS4-1; 4-PS4-3 · patterns in waves, and using patterns to transfer information

How we explain it

Children can open this short lesson before they practice.

  1. Waves have high points (crests) and low points (troughs).
  2. Amplitude is a wave's height. Bigger waves carry more energy.
  3. Wavelength is the distance from one crest to the next.
  4. Patterns like Morse code or digital code can send information.

Example: Which ocean wave has more energy: one 1 m tall or one 3 m tall? The taller wave has a bigger amplitude. Bigger amplitude means more energy. Answer: the 3 m wave

Waves & Codes in Alaska

In the Alaska content standards, this is unit 7 of 8 in 4th grade Science, after Energy, Speed & Collisions and before Rock Layers & Erosion.

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

    Sending a picture over the internet turns it into…

    • a sound only
    • water waves
    • a rock
    • a digital code

  2. Question 2

    Waves at the beach can move…

    • the moon
    • the sun
    • mountains in a day
    • sand and pebbles

  3. Question 3

    The low point of a wave is the…

    • peak
    • roof
    • crest
    • trough

  4. Question 4

    Bigger ocean waves have more…

    • color
    • salt
    • fish
    • energy

  5. Question 5

    Which wave has a longer wavelength?

    • Crests close together
    • A flat line
    • Crests far apart
    • No crests

  6. Question 6

    Which pattern could a ship use at night to send a message to shore?

    • Flashes of a light
    • Waving a flag
    • Painting the hull
    • Writing a note

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