They started off by putting two weetabix into a cup (the mouth) and grinding it up with the ends of pencils (teeth). They added water (saliva) to break down the biscuits. Then it was time to swallow and the mixture was poured into a plastic bag (stomach). Orange juice (stomach acid) was added and the bag was churned around until all the food was broken down. The bottom of the bag was cut open and the contents poured into the leg of a pair of tights (intestines). This is where it got rather messy. As the children squeezed the tights, some of the weetabix oozed out to represent what is extracted to be used around the body. Finally, the bottom of the tights were snipped off and the waste product removed. Lots of fun and giggles but also a lot of learning too.