Light Box Science: Baking Soda and Colored Vinegar
I grabbed one light box and the translucent tray to go on top. I also got out some baking soda, food coloring, and four 2 oz squeeze bottles filled about halfway with vinegar and gathered the children around the light box on the kitchen floor.
We reviewed what happened when we mixed water and oil on the light box (they stay separate). I explained that this time we were going to put colored vinegar on baking soda. I let them taste the vinegar and the baking soda. They claimed they liked both. I had them make a guess about what would happen when we dripped colored vinegar on the baking soda (their guess was that the baking soda would get wet and turn colored).
We chose four colors of food coloring and colored the vinegar in the squeeze bottles. I also used some leftover colored water for contrast. I sprinkled a rather thick layer of baking soda in the translucent tray and began by dripping some colored water on the baking soda and asking them to tell me what happened. They decided that the baking soda was wet and colored just like they guessed.
Then we tried the colored vinegar and got colored bubbles. We decided that when vinegar combines with baking soda we get a different reaction than when water mixes with baking soda. Vinegar makes bubbles and water does not. That was as complex as we got.
They were quite impressed and couldn't wait to play themselves. I handed them squirt bottles and let them begin.
Ava discovered that if she mixed yellow and blue she could make green bubbles. That was a lot of fun. The next time I try this activity I think I'll give each child three bottles with red, blue, and yellow and encourage them to mix colors as they go.
At one point the first tray of baking soda was completely saturated and I quickly rinsed it out dried it. We distributed a much thinner layer the second time and tried to make actual designs.
Cleanup was as easy as rinsing the tray out and drying it with a cloth.