How did this model help you to understand how the lungs work?

As part of our Science topic about the Circulatory System, the children have made models of a lung, using a plastic bottle and 2 balloons. They were able to use vocabulary such as 'diaphragm' , 'oxygen' and 'trachea' to explain this. It was quite tricky to stretch the balloons correctly and the children needed to persevere to complete it but many did, and they were excited to watch the inner balloon expand.