Alongside Optima Maths in KS1, we introduce Maths Mastery concepts. Increasingly, children are required to reason, problem-solve and discuss methods. We encourage our children to explain how or why something may have happened.
We "over-teach" core concepts such as number and place value and the four operations. Children are expected to have the language to reason regularly, and it can take time for them to develop the skills and confidence to do this, but as they leave KS1 and progress through KS2 maths, this approach really pays off.