Teachers' notes

When the stone is in the water, the reading is lower than in air. The water seems to push upwards on the stone, trying to make it float. Will the stone float?

• Find some different things to weigh. Here are some ideas:

a stone, a nail, a piece of wood, a cork, a pair of scissors.
• Lift them one at a time, to feel their weight. Put them in order, from lightest to heaviest. 
• Now check your idea: Use a Newtonmeter to weigh each thing. Were you correct? 

• Divide the things into two groups: things that will float and things that won't. 
• Test your idea.

• Now weigh each thing, in and out of water. Work out the force of the water pushing upwards on each object.