Formal addition requires the learner to add together numbers in columns. Essentially this is to ensure they add together the digits of the same order of value. E.g the tens are added together and the hundreds are added together etc. This concept of adding the same things can be introduced quite early and develops into a strategy much used in higher mathematics.
Exchanging
Being able to count to twenty involves the use of tens and ones. So learners experience the concept of place value probably before they truly understand its meaning. But the use of manipulatives such as Dienes blocks are essential for learners to fully grasp what place value means. This would usually start with exchanging ten ones for one ten.
Place value: Hundreds, tens and ones
Once learners begin to use three digits they can start to fully appreciate the importance of place value but it is still important for learners to be exposed to manipulatives such as Dienes blocks or place value counters
Column addition and subtraction
The purpose of setting out calculations into columns is to make the process easier, but learners need to fully understand why they are following a process so it is important for mentors to help them understand and not just follow a set of procedures without thinking.
As before it is important that learners have the opportunity to develop their understanding through using manipulatives and visual representations alongside the symbolic numbers before they are asked to only use the abstract symbols on their own.