A ==Key Stage 2=====Meaning===The [[air]] is what we breath in. ==Key Stage 3=====Meaning===The [[air]] is a [[mixture]] of [[gas]]es that we breath. ===About the Air===: The main [[gas]]es are; [[Nitrogen]] (78%), [[Oxygen]] (21%), [[Argon]] (1%), [[Carbon Dioxide]] (0.04%) and [[Water Vapour]] (% varies). ==Key Stage 4=====Meaning===The [[air]] is a [[mixture]] of [[gas|gases]] es that we breath. ===About the Air===: The main [[gas|gases]] es are; [[Nitrogen]] (78%), [[Oxygen]] (21%), [[Argon]] (1%), [[Carbon Dioxide]] (0.04%) and [[Water Vapour]] (% varies).