Structure of the atmosphere
The atmosphere is the envelope of air around the Earth. Air is about 78% nitrogen, 21% oxygen and about 1% argon, carbon dioxide and other gases, plus water vapour and dust. The atmosphere protects Earth from overheating by day and freezing at night, absorbs harmful ultraviolet rays from the Sun and burns up most meteors before they reach the ground. The lowest layer is the troposphere: about 8–9 km thick over the poles, 10–12 km in the temperate zone and 17–18 km at the equator. All clouds, rain and wind are here and so do people live here; with height the temperature drops by about 6 °C every 1000 m. Above it is the stratosphere (up to about 50 km), which holds the ozone layer that absorbs harmful rays. Higher still are the mesosphere, thermosphere and exosphere; the air there is very thin and polar lights appear in the thermosphere.
Atmosphere layers model: draw the Earth on A4 paper, then add the layers as coloured bands in order (troposphere, stratosphere, mesosphere, thermosphere, exosphere) and write on each its approximate height and what happens there (clouds, ozone, polar lights). Safety: use scissors carefully and keep paint and glue out of mouths.