- Review pupils' ideas of upthrust and density by showing a helium balloon rise or by using similar stimulus material.
- Build a (tethered) hot-air balloon using 'night lights' as the source of hot air, or build a windmill suspended from a thread to be driven by the hot air rising from a 100W light bulb. Establish that these work because heated air moves upwards since it is less dense than cooler air, and point out that the air will come down as it cools.
- Use forceps to drop a crystal of potassium manganate (VII) down a glass tube into water, which is then warmed over a Bunsen burner, and observe the trail of purple water formed due to the convection current. Alternatively, place a bottle containing cold, colourless water on top of a bottle containing hot coloured water, so that the contents can mix. Repeat with the bottle containing the cold colourless water on the bottom.
|
|
- recognise common hazards and work safely with flames and hot light bulbs
- choose apparatus to undertake a successful design-and-build exercise
- describe how air or water moves when part is heated or cooled
|
