Here's some pictures…
Take a ziploc bag and add a cracker and a half piece of bread (our bags were sandwich size).
It's nearly impossible to get this boy to make a good smiling face and they were already preparing themselves for the gross part of the experiment. :)
Jadon's gross face.
Add 1/2 cup vinegar to simulate stomach acid. I liked using an acidic substitute, but water would work, just not as fast.
Mash the food around with the vinegar with your fingers to simulate the stomach muscle action.
Within minutes our food is mixed and mashed into bits and ready to go into our small intestines! ;)