Key Maths is a series of graded activity books that reinforce children's mastery of important skills and concepts as required by the Primary National Strategy for maths at Key Stage 1. Areas covered include algebra, measures, money, fractions and data handling. Key Maths Book 2 includes: using a number line to count on/back and find the 'difference' between numbers, addition and subtraction, non-standard units of measurement, comparative measures (heavier/lighter), telling the time using half-past the hour and counting money and giving change.