Mastering Number is a NCETM (National Centre for Excellence in Teaching Mathematics) backed programme that has a daily taught sessions relating to the children's fluency with key number facts. It moves slowly, uses repetition and repeated refrains to ensure that children develop a sound understanding of each step before moving on.
Mastering Number at KS1 is used in Year 1 and 2 for their fluency sessions daily. These are extra maths sessions that focus on the children's ability to manipulate numbers and use them in a variety of contexts and problems.
In Years 4 and 5 the children use Mastering Number at KS2. This is also an extra daily session but this time it focusses on multiplication and division facts.