Sink or Float Experiment: Predict and Test

Six real objects are pictured down the left of this 1st grade page, each with its name: a bolt, scissors, a soccer ball, pliers, a pumpkin and a toy boat on the sheet shown. Beside each are two small water tanks, headed My guess and The test, and a star under Surprise. Every tank has two dashed rings, one at the water's surface and one resting on the bottom. A key at the top shows that an object at the surface floats and one on the bottom sinks. Before testing, the child colors a ring in the guess tank; after dropping the real object in water, a ring in the test tank; and if the two do not match, the star.

The page is built around one science habit: say what you think before you look. Writing the guess down first means a surprise is real, and the star makes surprises something to be proud of rather than a mistake. The objects are chosen to cause a few. Metal tools sink, the soccer ball and the toy boat float, and the pumpkin, big and heavy, floats as well, which is the result most children get wrong.

You need a tub of water and the objects, or objects like them. Test them together at the front, one at a time, and let children color after each splash. The lower ring rests on the tank floor, just like the sinker in the key, so children can see that it means the object went all the way down. This is the base page of the sink or float family; its faces test weight on a scale, reshape clay, check true or false claims, draw and write a lab report.