Our weather is constantly changing and this can have an impact on our lives. Storms can be dangerous for fishing boats and coastguards study weather charts so they can warn against adverse conditions. Atmospheric pressure is measured in milibars and is represented on weather maps as isobars. When the air is cold, the molecules are packed tightly together; the air becomes denser and begins to sink. The air now presses on the earth surface bringing high pressure. When the air warms, the molecules fly further apart; the air becomes lighter and rises, creating low pressure. High pressure often brings fine weather, but low pressure draws moisture from the ground creating clouds, rain and storms. Wind is caused by air moving from high atmospheric pressure to low atmospheric pressure.

Students could suggest whether conditions outside are the result of high or low pressure. They could watch a weather forecast to look for relationships between pressure and the weather that results.
Given a range of weather charts, students could predict the weather that will result.
They could keep a record of weather for a week and plot the changes on a graph of relative air pressure.