S2.5.7 For the adult
Floating and sinking
Why does a big log float but a tiny stone sink?
What this chapter teaches
Water pushes up on anything put in it. This push is called upthrust. A thing floats when the upthrust matches its weight before it goes right under. Heavy things can float and light things can sink, because it depends on what a thing is made of and on its shape.
Three questions to ask
There is no one right wording. Listen for the idea.
- Why might a big heavy log float while a small stone sinks?
- What push balances the weight of a thing that floats?
- How would you test which things in your home float?
After the chapter, the learner can
- Predict and test which objects float or sink in water
- Explain that water pushes up on things put into it
What they copy into their notebook
Water pushes up on things in it. This is upthrust. A thing floats if upthrust matches its weight before it goes under. Heavy things can float and light things can sink. It depends on what a thing is made of.