Ben said he wanted to make a volcano . . .

So we did...

This was the mom version

This was the mom version after chants of

 "more baking soda!" "more baking soda!"

Then I asked myself, "how often do I really use that apple cider vinegar?" and "that baking soda's sure been in the fridge a looong time, so..."

Have at it boys...

Now there's a volcano!

Great idea, Ben.  Good fun!!