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8th grade · Science · Unit 15 of 16

Light & Radiation

Waves, the spectrum and how light behaves

What your child practices

Wavelength and frequency, the electromagnetic spectrum from radio waves to gamma rays and what each is used for, reflection, refraction and color, and staying safe from UV radiation.

Alabama Course of Study content standard: 8.17 · wave properties of light and other electromagnetic waves

How we explain it

Children can open this short lesson before they practice.

  1. The electromagnetic spectrum, from longest to shortest wavelength: radio, microwave, infrared, visible light, ultraviolet, X-ray, gamma.
  2. Shorter wavelength means higher frequency and more energy.
  3. Light reflects off mirrors and bends (refracts) when it passes into a new material. Block UV with sunscreen and shade.

Example: Which has a longer wavelength: radio waves or X-rays? Radio waves are at the long end of the spectrum. X-rays are near the short end. Answer: radio waves

Light & Radiation in Alabama

In the Alabama Course of Study, this is unit 15 of 16 in 8th grade Science, after Circuits & Static and before Energy Transfers & Waves.

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: Alabama State Department of Education (ALSDE)

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 type of radiation causes sunburn?

    • microwave
    • infrared
    • ultraviolet (UV)
    • radio

  2. Question 2

    Why is a red shirt red?

    • It reflects all colors.
    • It reflects red light and absorbs most other colors.
    • It makes red light.
    • It absorbs red light.

  3. Question 3

    Put these types of electromagnetic radiation in order from the longest wavelength to the shortest.

    • 🩻X-rays
    • 🍿Microwaves
    • 🌡️Infrared
    • 📻Radio waves

  4. Question 4

    Which type of radiation is used to heat food in a microwave oven?

    • microwaves
    • ultraviolet
    • gamma rays
    • X-rays

  5. Question 5

    Which has the shortest wavelength?

    • microwaves
    • gamma rays
    • visible light
    • infrared

  6. Question 6

    Which has the longest wavelength?

    • X-rays
    • radio waves
    • visible light
    • ultraviolet

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