Mental Strategies in Year 5 Maths

In Maths, we’ve been looking at our mental strategies for addition. It’s great to discover lots of interesting ways of doing Maths and the more strategies we have to hand, the better! We want to find strategies that help us to solve problems quickly and easily so to begin with, we practised using number lines for counting on in 10s, 100s, 1000s and 10000s. We had to add 7,000 to 4,000 which meant we had to decide which power of ten to count in and how many times. By jumping seven times along the number line in 1000s we could conclude that 4,000 + 7,000 is 11,000:

Next the children were asked to use their number lines to add 2 digit numbers togethers. This meant we had to partition the numbers first and jump along the number line in tens before jumping along the number line in ones:

Once the children had sufficiently practised using number lines, we moved our attention to another physical representation: part-whole models. Part-whole are an excellent way to visualise partitioning and we used part-whole models to answer the question 24 + 69. Once we had partitioned the numbers, we realised we had 8 tens altogether and 13 ones. Once these were added together, we were left with an answer of 93!

As we were comfortable adding 2 digit numbers in our heads, we started to look at strategies for adding even bigger numbers! We were given the question 672 + 99 and realised that 99 is very close to a multiple of 10, which we can add easily in our heads. We decided to use our number lines again and jump 100 to 772. We could see that we had added one too many and that meant we had to jump backwards (subtract one) on the number line to find our answer!

After plenty of whiteboard practise, we were ready to apply our skills to our Power Maths Practice Books, solving a range of addition problems using mental strategies!