This was a fun little after-school science activity. I had the things I needed ready before B came home from school: a small plastic bottle, a bottle of vinegar, a jug or another old bottle, bicarbonate of soda (baking soda), a teaspoon and red food colouring.
Once B was home, we took everything outside. We put the small plastic bottle on the ground and packed some sand around it from the sand table, which made it look like a mountain, with the opening to the bottle exposed like a crater. Then I let B put a couple of heaped teaspoons of bicarb in the bottle. I poured some vinegar and food colouring into the old plastic bottle (which we used as a jug) for B to pour into the mountain. It worked a treat! We experimented with different amounts, which changed how quickly or slowly it came out. Sometimes we had quite a violent volcano, other times it was a slow ooze. Not enough of either bicarb or vinegar and it didn’t really work. We ran out of vinegar far too soon, we could have kept going for ages!
No doubt we will do this again sometime soon, and perhaps try a different shape or size bottle, maybe a bigger bottle with a thinner neck/opening. And we’ll make sure we have plenty of vinegar!