Energy systems


8. Things that Glow in the Dark


Students discover how an ultraviolet (UV) LED can make a fluorescent pattern glow in the dark. Then they learn about how different forms of radiation are related, including ultraviolet, visible and infrared light.

Advance Preparation

  • Make a simple circuit with an ultraviolet (UV) LED and two coin batteries, and use it to light up a “secret message.” Save the components for a classroom demonstration. See a video and diagrams showing how. Make a chart showing the circuit diagram.
  • Make a chart labeled Different Forms of Radiation, with the headings “Infrared”, “Visible Light” and “Ultraviolet”. Leave space for additional headings.
  • Photocopy worksheet and assessment (downloadable at bottom of page).


Per pair of students:

  • Ultraviolet (UV) LED, two coin batteries

General Supplies:

  • Paper fasteners, tape, hook-up wire, strippers, tape, rubber bands
  • Fluorescent markers (yellow hi-lighters), cardstock in assorted colors, small boxes
  • craft materials


  1. Things that glow: Demonstrate how to light up a secret message using a UV LED.
    If possible, have someone turn off the lights so the effect is more dramatic. Conduct a discussion about what is happening:

    • What is making this glow?
    • How could you use this idea?

  2. Make something that glows in the dark: Provide materials and time for students to make their own images and messages that can glow in the dark.

  3. Different forms of radiation: This lesson uses ultraviolet (UV) light and the next one will focus on infrared (IR) light, so this is a good opportunity to discuss different forms of light and of other kinds of radiation (see a video). Ask students:

    • What do you know about infrared light, visible light and ultraviolet light ?
    • What is the effect of each kind on us?
    • What can each type be used to do?

Chart their observations. Explain that these are all forms of radiation, and ask:
* What other forms of radiation are there?
* How is each type of radiation produced?
* What can it be used for?


Worksheet: Things that Glow in the Dark

Things that glow.docx


If the secret message or image glows but is too dim, some things to try are:

  • Make sure there are two coin batteries in series (see a video)
  • Use a different background color (see a video)
  • Turn off the lights or find a darker place.

If the UV LED doesn’t come on at all, check to see that the batteries are stacked correctly (see a video). To learn more about this issue, you can use the Digital Multi meter – click here to explore further.