Balloons

The balloons they brought home, though, are filled with something called helium.

Apparently, it's so much lighter than air that if you let one loose, it would just float up into the sky for ever and ever - the teddy bears think probably even as far as the moon!! The balloons themselves are made of some material that is very light - and looks a bit like tinfoil that has been painted all over in pretty colours! That's why each balloon has a ribbon tied to it, with a weight on the end so that they can't float away!