I love this activity. I agree that it is totally child centered and a wonderful catalyst for deeper inquiry and discussion. It’s very hands on and it’s a great experiment for the classes.
It’s a particularly exciting one as I’m sure some children will predict that balloon will burst and the discussion around why it doesn’t will be fascinating for them. There’s also wonderful ‘tension’ in the lesson as well with the anticipation of popping balloons which makes it extra engaging!