This half term, Chestnuts have been learning all about the importance of the digestive system in humans and our teeth. We decided to find out which drinks would cause the most tooth decay. We conducted an investigation by using hard boiled eggs in different liquids and we observed how they changed. We were surprised to find orange juice caused a lot of damage to the egg and we thought this may be because of the acid in it as well as the natural sugars. Water and milk were the best liquids we investigated.