Free PDFGrade 5 · Science · 40 min

Smoke in the water

Hot blue water rises like smoke through cold water.

I can explain convection: why warm water rises and cold water sinks.

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Worksheet Answer key

About the video

In the video hot blue water rises like smoke through a jar of cold water. At home your child lowers a small foil covered jar of hot blue water into 1.5 litres of cold water, pokes 2 holes in the foil and times how long the blue water takes to reach the top, then repeats it with cold blue water.

In hot water the particles move faster and spread a little further apart, so hot water is less dense than cold water. The cold water sinks and pushes the hot water up, and this movement is called convection, which also happens with warm air above a heater.

What your child learns

Explain why hot water rises and cold water sinks
Use the word convection to describe moving water and air
Compare a hot and a cold try with a timer

What's on the worksheet

1Predict first
2Record your tries
3What did you see?
4The science behind it
5Match the words
6True or false
7Rise or sink?
8Water maths
9Draw and label it

You need

1 big clear jar (about 2 litres) with 1.5 litres cold tap water, 1 small glass jar (about 100 ml), 100 ml hot tap water, 3 drops of blue food colouring, 1 piece of foil 10 cm × 10 cm, 1 rubber band, 1 string 40 cm long, 1 wooden skewer and a timer.