An ==Key Stage 2=====Meaning===The [[brain]] is an [[organ]] that can think and controls the rest of the body. ==Key Stage 3=====Meaning===The [[brain]] is an [[organ]] that can thinkand controls the rest of the body. ==Key Stage 4=====Meaning===The [[brain]] is an [[organ]] in the [[Central Nervous System|central nervous system]] which coordinates and controls the rest of the body.