Your child will use predictions and observations to determine whether objects will sink or float when placed in water. Your child will also be introduced to vocabulary, such as sink, float, predict, and experiment.
Begin by introducing the activity, saying something like, “Do you know what it means to float?” Relate this concept to swimming or bathing in a bathtub. You can explain that “When something falls to the bottom of the water, we say it sinks. If it stays at the top of the water, we say it floats.” You can also introduce the term experiment and explain that when we try things out to see if our ideas are correct, this is called an experiment. You can tell your child that you will be doing an experiment together to see which items float in the water and which ones sink.
Fill a tub with water. To demonstrate the activity, you can first ask your child to predict if a rock will sink or float. Say, “A prediction is a guess. It is what someone thinks will happen. Do you think this rock will sink or float?” You can then carefully put the rock on the top of the water. Confirm if she was correct or incorrect in her prediction and discuss conclusions. Discuss real world connections, for example, a past experience when your child saw rocks sink when thrown in a pond or puddle, or how rocks rest at the bottom of rivers and streams.
Next, introduce your child to the household objects one at a time. For example, “This is a cork. Do you predict that this will sink or float?” Place the object on top of the water and observe what happens.
You can discuss with your child how her predictions matched her observations, emphasizing the words float, sink, predict, and experiment.