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8th grade · Science · Unit 5 of 9

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.

Arizona Academic Standards learning standard: 8.P4U1.4 · wave properties and how waves interact with matter

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 Arizona

In the Arizona Academic Standards, this is unit 5 of 9 in 8th grade Science, after Work, Energy & Efficiency and before Genes & Heredity.

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: Arizona Department of Education

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 travels fastest?

    • a jet plane
    • a car
    • sound
    • light

  2. Question 2

    Which material lets light pass through easily so you can see clearly through it?

    • reflective
    • transparent
    • translucent
    • opaque

  3. Question 3

    Which has the shortest wavelength?

    • gamma rays
    • microwaves
    • infrared
    • visible light

  4. Question 4

    Which type of radiation is used to take images of bones?

    • X-rays
    • infrared
    • radio waves
    • microwaves

  5. Question 5

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

    • 🍿Microwaves
    • ☀️Ultraviolet
    • 📻Radio waves
    • 🌡️Infrared

  6. Question 6

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

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

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