Year 1 performed a science experiment, where they made balloon rockets! They did this by threading string through straws and attaching the string to two chairs. They then blew up balloons, making sure the air didn't escape, and carefully attached the balloons to the straw. When everything was ready, they released the balloon to send it rocketing across the string! We discussed that the air in the balloon was sending the balloon forwards as the air released.
The children found that it was important to start the balloon at the correct end of the straw, because if there was no space for the releasing air to propel it forward, it simply spun in circles!