Alas, poor Ya-Ya, the very best of intentions don't always pay off when it comes to achieving successful outcomes to science experiments!
One afternoon while I was lying down my friend attempted to recreate for my boys the "Mentos in the Coke bottle" fountain/volcano. However Mt Vesuvius was decidedly dormant - even shaking the bottles vigorously, or adding copious amounts of bicarbonate of soda and shaking again, didn't seemed to entice even a tremor, let alone a pyroclastic eruption.
Upon viewing the photographs which my long suffering friend had taken of the experiment, a clue was discovered as to the reason for the disappointment. And, upon chatting with another homeschooling family, who have a science aficionado for a son, the light of understanding was shed upon the matter.
I have three sons, and my friend had decanted equal quantities of the cola into separate smaller bottles so each could have their own. When they added their Mentos lollies and nothing happened they shook the bottles vigorously, and when that didn't work they added copious amounts of bicarbonate of soda and shook again, but still to no avail and much disappointment.
It all has to do with the amount of carbon dioxide in relation to the size of the lolly - when the carbon dioxide in the Cola is the suddenly/instantaneously attracted to the coating of the Mentos it has nowhere else to go but up and out of the bottle, at a great rate of knots.
Hmm, I wonder if it would work on lollies other than Mentos? Sounds like science experiment No.3 coming up!