Rose made an interesting comment this week
"it's full of air so it's not heavy - it doesn't weigh anything"
I knew we'd discussed the weight of air vs helium previously but thought I should come up with a quick recap for Rose.
I made a hanging scale from a lollipop stick, some string and a nail. Next took two balloons and blew on of them up - we stuck a balloon to each end of the scale and observed.
She now knows that while air may be light it does at least weigh something : )