My baby boy (here 6 months old) are very interested in balloons.
Probably because of this one’s bright colours and the reasonable size, it attracted his attention quickly.
This foil balloon was filled with helium for sisters party, but stayed up for a whole month! He enjoyed looking at it at first, but then I tied it around his hand so when he moved his hand, so did the balloon and it made a sound! (Teaching reaction on action)
Best part for me was the location, because the sun made some interesting reflections catching the foil of the balloon…