Foxes class have been answering the question: How do we know gas exists?

We weighed a balloon empty and with air in, we made the feather move (as shown here by Felicity) using a fan, we used gas to help us smell products like spices, scented candles and fruit, squeezed the water out of a sponge and had a think about how we know the gas is there? Can you explain these investigations?

Have a go at these sorting games here: https://www.topmarks.co.uk/Flash.aspx?b=science/gases

and here: http://www.bbc.co.uk/bitesize/ks2/science/materials/gases_liquids_solids/play/