Students at this grade level understand the concept of sinking and floating. What challenges them is the WHY...why does one thing sink and another thing float. The students often attempt to make generalizations to assist them with answering the WHY. Some say that it is WHAT the item is made of. The generalization may be that an item made of wood will float and an item made of metal will sink. Some generalize that it is the WEIGHT of an object that allows it to float or sink, so a toothpick is light and floats, but a nail is heavy so it sinks. The challenge in this lesson, was to make a plastic lid, which floats, SINK.
The students could choose from the items we have in our science kit, and hopefully use their knowledge from the previous science lessons, to assist them with making the lid sink. The young man who put the plasticine on the bottom was SOOO surprised when the lid still floated!
Here's an example of a sunk lid....with plasticine and nails on the top!
The students have not yet figured out WHY large cargo ships, made of metal, with tons of cargo on them, can stay afloat. It is through these experiments that we will be trying to figure that out.