Make your own poo!
ZT learnt how the digestive system works by creating his own poo: first he cut up food with scissors, representing biting; mashed it up, representing chewing and added water as saliva. He represented swallowing the food down his 'oesophagus'; he squashed it up and added vinegar as bile in the stomach, he put it what was left in a pair of tights to be the intestines and squeezed out the liquid; just like his body takes in the nutrients it needs and then finally, he pushed the remaining, drier mixture out as a poo showing the bits his body doesn't need!