a light soft silver-white metallic element of the alkali metal group; oxidizes rapidly in air and reacts violently with water; is abundant in nature in combined forms occurring in sea water and in carnallite and kainite and sylvite
Key Stages within the National Curriculum; pupils are phased under key stages 1, 2, 3, and 4, the phases ending at the close of the school year in which the child becomes 7, 11, 14, and 16 Thus key stage 1 covers ages 5 - 7, and so on