Today, we had maths expert Lynda Keith in school. She spent time in our class on strategies for mental addition.
We found lots of different strategies for solving the same calculation. Some of the strategies we used were:
- Counting on and Back (CO)
- Partitioning (splitting) a number (P)
- Rounding and Adjusting (RA) or Bridging and Adjusting (BA) – Looking for numbers that are close to a multiple of 10, so that you can round to a multiple of 10
and then add or subtract a small number (adjusting). For example:
64 + 79 = 143 Work this out as 64 + 80 − 1 = 143
138 − 47 = 91 Work this out as 138 − 50 + 3 = 91
We practised using empty number lines and partition grids.
We know that we don’t always have to go straight to the column method to work out calculations. There may be a quicker and easier mental strategy, so we should always look at the numbers first to see if we can spot any number bonds we know, any doubles, near doubles or connections.
