How Things Work 3-minute video · ages 4-8 · free coloring page
How do glow sticks glow?
A glow stick has no battery, no wire, and no switch. You just bend it, shake it, and it glows. How does that work?
3 min
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Free coloring page
The scene from the video as a coloring page, plus the three-sentence answer, the experiment, and a QR code back to this page. One sheet, US Letter, black and white.
The answer in three parts
Why?
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Snap! Two liquids mix.
A glow stick is a plastic tube filled with a liquid. Floating inside is a thin little glass tube, with a different liquid in it. When you bend the stick, the glass tube cracks. Shaking helps the two liquids mix all the way.
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Mixing starts a chemical reaction.
Tiny bits of the two liquids bump into each other and change into new stuff. As they change, they give off a little bit of energy. That energy gets handed to the color in the stick, called a dye.
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Electrons jump up and fall down, and make light.
When an electron in the dye gets the energy, it jumps up high, like a kid on a trampoline. Boing! Then it falls back down, and lets the energy go as a tiny flash of light. Millions of electrons do this again and again, and the whole stick glows!
For grown-ups: A glow stick does not get hot like a light bulb. It makes cold light, which scientists call chemiluminescence: light from a chemical reaction. After a few hours the liquids get used up and the glow fades; it can't be turned back on. Never cut a glow stick open - the liquid inside is not safe to touch or taste.
Different dyes, different colors
- Green
- Pink
- Blue
A tiny experiment
Try it!
Warm or cold?
You need: two glow sticks of the same color, a cup of warm tap water, a cup of ice water, and a grown-up
- With a grown-up, snap two glow sticks of the same color.
- Put one in a cup of warm tap water, and one in a cup of ice water.
- Turn off the lights. Which one glows brighter? And which one lasts longer?
What happened? Warm makes the reaction go faster, so the stick glows brighter but runs out sooner. Cold slows it down, so it glows dimmer but lasts longer.
Did you know?
Nature can do it too! Fireflies make light inside their bodies with a chemical reaction. They blink their lights to say hello to each other on summer nights.
A glow stick makes cold light. It does not get hot like a light bulb!
Your guide in this video
It's me, Zippy, a tiny electron. I love glow sticks! Let's find out how they light up.
Zippy is a tiny round blue electron with a yellow spark on top. There are electrons just like Zippy inside the dye of every glow stick!
For grown-ups
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