1.   He spun tops and played with rubber balloons.

2.   That is because the rubber balloon, called a boot, itself disrupts the smooth flow of air across the wing, making it less efficient.

3.   The boots are thick rubber balloons on the forward edges of the wings that alternately inflate and deflate to break off accumulated ice.

4.   The boots are on the forward edges of the wings, thick rubber balloons that alternately inflate and deflate to break off accumulated ice.