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8th grade · Science · Unit 2 of 10

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.

Minnesota K-12 Academic Standards benchmark: 8P.2.2.1.1; 8P.3.1.1.4 · waves, and how light is reflected, absorbed or transmitted

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 Minnesota

In the Minnesota K-12 Academic Standards, this is unit 2 of 10 in 8th grade Science, after Particles & Matter and before Atoms & Elements.

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: Minnesota Department of Education (MDE)

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?

    • infrared
    • ultraviolet (UV)
    • radio
    • microwave

  2. Question 2

    Which has the shortest wavelength?

    • infrared
    • microwaves
    • visible light
    • gamma rays

  3. Question 3

    Which travels fastest?

    • a jet plane
    • light
    • sound
    • a car

  4. Question 4

    A wave's wavelength is…

    • the height of the wave
    • the speed of the wave
    • the number of waves in a second
    • the distance from one crest to the next

  5. Question 5

    Why do we see white light split into colors in a prism?

    • The prism adds paint.
    • The prism makes new light.
    • Light changes into sound.
    • Different colors bend by different amounts when they refract.

  6. Question 6

    Light can act as both a wave and a stream of particles. What are the particles called?

    • electrons
    • protons
    • photons
    • neutrons

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