Balloon Won't Inflate in Sealed Bottle

Balloon is hard to inflate until air can escape. Ask students to predict what will happen. Try inflating a balloon inside a sealed bottle, then open a small vent hole. Key idea: Air already in the bottle takes space and pushes back. Ask: What is stopping the balloon? Safety and cleanup: Teacher controls any pre-made hole. https://www.creativeeducation.co.uk/wp-content/uploads/2021/01/Resource-B.1-Guide-to-Experiment-Bottled-Balloons.pdf