Glow Stick Investigation

Glow stick dipped in hot water

Glow stick dipped in hot water

Glow stick dipped in hot water, then again in cold water at the bottom. You can see the difference!

We continued our discussion of the behavior of atoms this week with a glow stick investigation. We activated our glow sticks by popping them, making the liquids inside interact to cause the glow. Then we dipped the glow stick in hot water, and it immediately got much brighter. We discussed the reason for this was because those atoms are getting more and more energized by the thermal energy, so the chemical reaction causing the glow was happening faster. When we dipped the glow stick in the cold water, the color immediately dulled due to the loss of energy. The atoms began to slow down. Fun activity!

Particles in Different States of Matter

Our particles made out of stickers

We've been discussing ways to classify matter, and one way is by states of matter. By the time I get 4th graders, they've had lots of exposure to solids, liquids, and gases. Determining the state of matter for an object is nothing new. It's my job to introduce how heat can affect a state of matter, and what happens to the particles as the state changes.

We began by marking off a "jar" on the floor. We just used chairs as our boundaries. We packed ourselves into the "jar" and pretended to be the particles of a solid block of ice, frozen in a jar in the freezer. We were all touching, and no one was really moving much. Then we pretended someone took us out of the freezer and sat us down on the counter of a comfortably-warm room, so we started to slowly melt into a liquid. We began to move around and bump into each other, still within our jar. Finally, someone held us over the stove, so we began to move faster and faster, bumping into each other and the walls of the jar, until finally we became a gas and came out of the jar and flew around the room. We compared the particles of a gas to a sugared-up toddler. Ha ha!! Then we went in reverse and eventually became a liquid, then a solid again.

Popcorn Lab

Frozen "solid" of shortening and kernels

 The purpose of the popcorn lab was for the kids to have a visual example of what atoms look/behave like in all three states of matter. We began with a frozen "solid" of shortening with kernels (our atoms) packed in it.  The atoms are tightly packed in, and aren't moving. Then I challenged the kids to, without opening the bag, make their solid a liquid by adding thermal energy. They quickly figured out rubbing the solid was the fastest way to do this. After the solid became a liquid, we observed the atoms and noticed they were looser, not all touching, and moved around in our bag. Finally, I took a solid out of its bag and placed it in a beaker on a hot plate. We quickly got to see the solid changing states. As more and more thermal energy (heat) was added, the atoms finally became so energized they couldn't be contained in the beaker any longer and tried to escape. We kept this from happening with the foil.

After we finished our investigation, we discussed why these things happened to our atoms. The thermal energy gives the atoms so much energy, the result is the atoms becoming more and more active. This causes the change in states. We also discussed what this would look like if we removed thermal energy and went in reverse.

The solid beginning to melt

Liquid form

Student journal sheet page 1

Our "gas"

Student journal sheet page 2

Student journal sheet page 3