Fill your sink or a bucket with water. Make a chart, like the one in the video, and experiment to see what sinks and what floats. As you do this, ask about the density of the object:
- Does this mean that the object is more or less dense than the water? (If it sinks, it is more dense. If it floats, it is less dense.)
- If the metal spoon sank but the plastic spoon floated, what can you tell me about the plastic spoon? (it’s less dense than the metal spoon)
Now we’re going to do an experiment with salt water. Go to this website which gives you instructions on how to do the experiment.
As you’re doing the experiment, talk about the eggs in each glass. Ask and answer questions, remembering the video at each step, and give prompts to help your child work out what is going on:
- Can you remember the video? Why did the metal spoon sink? (because it’s more dense than the water)
- Look at the egg in normal water. Why has it sunk?
(because it’s more dense than the water)
- Look at the egg in the salt water. Why is it floating?
(because it’s less dense than the water)
- The two eggs are exactly the same so what has changed? What can you tell me about the salt water, compared to the normal water?
(the salt water must be more dense/have a higher density – it must be more dense than the egg)
- Why might the salt water have a higher density than the normal water?
(because of all the salt particles that have mixed with the water particles!)