This maths worksheet for year 2 children looks at pairs of numbers which make 20. Before doing this children should be confident with, and know by heart, all pairs of numbers which make 10. Once they know these, pairs that make 20 becomes easy; just one of each pair is ten more e.g. 6 and 4: 16 and 4. Being able to work quickly with mental arithmetic is one of the keys to success in school as so much of the maths lesson today is carried out orally and children gain or lose confidence very quickly when answering in front of a whole class.