Heavy or Light? Sink or Float on a Balance Scale

Four balance scales stack down this 1st grade page, and each weighs two things against each other. The tipped arm shows which is heavier. The child circles the thing that floats in water. On the sheet shown a potato outweighs a pine cone; an apple outweighs a nail; a rock outweighs a feather; and a thick log outweighs a small hammer. In two of the rows the thing that floats is the lighter one, the pine cone and the feather. In the other two it is the heavier one: the apple floats while the nail sinks, and the big log floats while the hammer goes down.

Almost every child believes heavy things sink. This page does not argue with that; it lets the scale and the water argue for it. Once the apple and the log have floated, children have to find another reason, and the conversation moves toward what things are made of and how much space they take up, which is where later grades take it. The page does not need the word density, and should not use it.

One sheet, four circles, and the floating object sits on the right in the first two rows and on the left in the last two. It is most convincing with the real objects: a kitchen scale or a classroom balance and a tub of water will do. Test the apple and the nail last. The base page of the sink or float family predicts and tests six objects; this face adds the scale.