Tomas is ten. He says, "Air has weight." His sister Elisa laughs. "Air is nothing!" Tomas puts a flat football on the kitchen scale. Then he pumps it hard. He weighs it again. It is a few grams heavier! Elisa checks the scale twice.
Their father says, "Air presses on everything." Tomas shows the class and wins a ribbon at the science fair. Elisa helps him. She is the "Head of the Air Department."