This is very cool! How much did everyone love lava lamps a few (decades?!) years ago?? So when I saw it here I had to try it out with the little guy!
So you’ll need:
An empty soft drink bottle
A bottle of Vegetable oil
An alka seltzer (or 10) tablet
A funnel (to make it easier, but not essential)
So, fill the bottle a third of the way with water, then fill the remainder with the oil