I will readily admit that this particular science project is not all that sciencey. There’s not a whole lot to really learn from this one, in the grand scientific scheme of things. But I feel that, if you haven’t made a DIY “lava lamp” with your students at least once, you’ve failed—not only the students, but yourself. So don’t complain about the lack of “real” science in this one and just get out there and do it because it’s your duty as an American educator in 2016. (Please note, if you’re not teaching in America, you are not obligated to do this one. Still, it’s a fun one, so maybe give it a shot.)
Please note that you will not be construction anything that close to an actual lava lamp. There will be no electricity involved, no wiring, no light bulbs, etc. This experiment simply mimics the look of a lava lamp in action.
For this Demo Science science-adjacent demo, you’ll need an empty two-liter soda bottle (how you empty that bottle is up to you, but DO NOT give Kevin any soda—his mom will figuratively kill you), about 3/4 cup of water, some vegetable oil, Alka Seltzer or other similarly fizzy tablets, and food coloring. A funnel might also be helpful. If you want to concoct a lava lamp for each student, obviously multiply your supplies by however many kids are in your class.
First, once the bottle is nice and clean, pour in the water. Then, slowly pour the veggie oil into the bottle (this is where the funnel comes in handy) until the bottle is nearly full. Chillax for a few minutes as the water and oil separate, which they will do automatically.
Splorp in about 10 drops of food coloring—any color is fine, but note that yellow won’t show up all that well. The food coloring will pass right through the oil and mix with the water. Once that’s all nice and mixy mixy, break an Alka Seltzer (or whatever you’re using) in twain and drop it into the bottle. As it sinks to the bottom and reacts with the water, the lava lamp-esque action will begin.
Stick a flashlight under that sucker to give more of a “real” lava lamp look. Drop in another Alka Seltzer to keep the blobs a bubblin’ and the bubbles a-blobbin’.