your own simple thermometer. a) a strong plastic bottle with a
scew cap b) a thin plastic straw c) some modelling clay d) a
sellotape; and e) some water coloured with poster paint. Ask an
adult to drill a hole in the bottle's cap. Assemble the
thermometer, making sure that the water comes part way up the
straw when you fix on the cap. Leave the water to settle for an
hour then mark the water level on the scale. Stand the
thermometer in a bowl of ice cold water and a bowl of very hot
water. See how the water level changes.