Light Blox Quick Start Guide

This is a short guide to your first experiment with our Light Blox! For dozens of more free lessons, download our full actitivties guide

How to operate the Light Blox:


Light Blox require 6 AA batteries. Install 2 AA batteries in each unit by sliding open the case and inserting batteries. Replace the battery cover. 


Turn on Light Blox with the switch on the side of the unit. Slide the switch to turn the unit on or off. The color emitted will match the sticker color at the end. 

Removable Caps:

Each Light Blox comes with a removable "slit-cap" on the front. When the slit-cap is on, the units produce a ray of light for exploring the path of light, reflection, and refraction. To view the beam path, orient the Light Blox so that it is sitting on the narrow side with magnets down, as shown. 

light blox LED ray box source for teaching optics

When the cap is removed, the units produce a block of light for studying color and shadows as shown:

light blox led color mixing educational tools in red green and blue


Run your first experiment:

Find these household materials:

  1. A clear glass with a flat bottom and smooth, straight sides
  2. A piece of white paper
  3. Masking or Scotch tape
  4. Batteries and Light Blox

Experiment instructions:

  1. Place the glass on a table, about 3" from a wall, board, or box. 
  2. Tape the piece of white paper against the wall or box behind the glass
  3. Turn on all three Light Blox with slit caps ON and shine the beams through the empty glass. Observe the beam shape through the glass,
  4. Now, fill the glass with water and see what happens: The beams switch places!

bending colors of light with a glass full of water


This happens because the water acts as a lens, causing the light that passes through it to bend. The glass is thicker in the middle and thinner at the edges, so it acts like a convex lens, which causes light to bend in this particular way. 

One more experiment with caps OFF this time:

Let's mix some colors of light! What do you think will happen when you mix green light with red light? 

Your first thought might be what happens when you mix red and green paint. Right? That gives you a yucky brown color. 

So what do you think will happen when you do the same with light? Pause and make a prediction!

Experiment instructions:

  1. Take the slit caps OFF all three Light Blox.
  2. Turn on the green and red Light Blox. 
  3. Move them so the two beams combine on a white paper or wall. 
  4. Observe the colors you see in the combined beam. What happened?? 
  5. Now, turn on ALL 3 (add the blue) and merge all 3 beams. What color did you make now?
  6. What happens when you mix red and blue, or blue and green? 

how to make white light from red green and blue light for kids


Lights add narrow wavlength bands of light together. A red bulb gives red light. A green bulb gives green light. A red and a green bulb give you red and green light. Your eye will see that combination as yellow because both red and green are reflected from the wall.

Paints subtract light. Red paint takes white light and absorbs all of it except the red light, which is reflected to your eyes. Green paint takes white light and absorbs all of it except green light. If you mix red paint and green paint, the red pigments will absorb all but the red, but the green will absorb that red so nothing will be reflected. Your eye will see that as the yucky brown.


Congratulations! You've done your first two experiments with Light Blox! Get the full lessons below WITH printable activities sheets by email: 

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