Idea 230: The Big ‘Mental Maths Chat’

Choose some single-digit numbers and ask who can find the answer:


DO NOT praise anyone who shouts out!

DO NOT even praise children who can get the answer quickly, ONLY praise them if they can explain their thought process to the class, with you scribing on the board what they are telling you to do. My pupils love describing what numbers they looked for and what numbers they added first.

For example, below are the steps of this problem that a child in my class told me, with me scribing the steps:


This is great to show that some children might use their times table knowledge, or some might look at doubling numbers, others might be red-hot on their number bonds, others might then use number bonds and go on to applying that and saying ‘well I know 7 + 3 is 10, so 7 + 4 must be 11!’.

AND another important point is that sometimes one strategy will work better than others. Like here:


I’d expect pupils to perhaps use their 5 times table knowledge here.

Whereas here I’d expect perhaps number bonds being used (5 and 5, 7 and 3, 8 and 2):


And here I’d expect doubling and perhaps number bonds (3+3 = 6, add 4 makes 10, then add the final 4 makes 14):


You might be surprised to find that unless this approach is explicitly discussed, some of your children will simply start on the left side of a calculation and painfully work their way through to the end, making the whole process a lot more challenging than it really needs to be!


TIP: Why not model to your class how painful it can be if you work through a calculation from left to right every time?

TIP: When you introduce this activity, you could perhaps show your children a calculation that you have done jottings on first, including the final answer. Instead of asking ‘what’s the answer?’ and so turning off your lower achievers, you can have the class discuss in pairs what they think is going on and what they can spot, using their reasoning skills. You can then ask for contributions to a class discussion of what they have noticed.

TIP: Tell the class you don’t even care if they get the answer wrong or don’t have time to finish, what you are interested in is them being able to describe how they’d begin!

TIP: Start off by allowing volunteers to tell you their thought process. When your class are comfortable with this task, choose students at random to contribute. If you do randomly choose a child who struggles with mental addition, remind them that you DON’T CARE about the answer, but just want them to tell you where they might begin. You can even ‘do the adding bit’ for them as long as they can guide you through the numbers they’d choose!

EXTENSION: As an independent task you can have children pull some random single-digit numbers out of a hat and then write a calculation, showing their working out as they go.


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