Tag: place value

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Teaching Column Addition and Column Subtraction

This is my lovely place value teaching tool. It was custom-made for me by my brother at Sen Clock and my dad. Prior to this I’d been using a paper sheet and laminated tokens, but I was fed up with them sticking together and getting lost. This magnetic version is much more practical.

I find this really useful because we if stick the tokens to the board, children have visual proof that once there are 9 tokens in a column there is no room for any more, so if they wanted to add another One in, it’s time to exchange 10 Ones, which won’t fit, for 1 Ten, which will. Physically clearing out the column, exchanging 10 One tokens for 1 Ten token really helps them to understand what happens when I want to add 1 to 109.

It’s great for subtraction too. When presented with – calculation lots of children will try to do 3-1. With this place value board, they can see that we only have one counter so we can’t take away 3. Then we can physically exchange 1 Ten for 10 Ones. I’ve made the column wide enough to accommodate them and the children can then see that they have enough in the column now to subtract 3, and that the tens column has one less token than it had before. I find this works really well side by side with a written column subtraction to iron out any misconceptions and to understand how the written method works.

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Teaching sequencing and column addition to a child with dyscalculia

Recently a colleague asked me for some suggestions to help one of his pupils with her maths. She was having various problems, such as

  • Difficulty with sequencing numbers
  • Getting confused as to which way to move on a number-line to add or subtract single digits
  • Getting confused as to which way to move on a number-square to add or subtract multiples of 10
  • Not understanding whether an answer she got when performing a calculation was “reasonable” or way off
  • Confusing the Hundreds Tens and Units columns and so not always starting in the correct place when performing calculations.

He suspected that the child in question might have dyslexia and / or dyscalculia, and if that is the case then I can understand why they might have trouble with column addition/subtraction. They’ll be concentrating really hard on left to right, left to right for their writing, and then suddenly column calculations go right to left – no wonder they get confused!

My advice was to make the learning experience completely multi-sensory, even if it meant taking the learning outside.   These were some of my suggestions:

  • Make a physical number line on the floor/front driveway/back garden/anywhere with plenty of space. Place one object with the label “1”, then two objects labelled “2”, three objects and a label 3 and so on to help her equate the number 3 with the value 3
  • Chalk the numbers outside, and get her to walk along it counting forward, and then walk the other way counting backwards.  Get her to jump along it landing on every other number counting forwards in twos and then backwards in twos.
  • Move on to a number square in chalk so that they can change direction to add on/take away 10. This should also help with “reasonable” answers because, for example, she would come to understand that she had to walk further to add on 49 than to add on 12.
    • Always make the number square start with 1 at the bottom, rather than at the top like most number squares – then the higher numbers are at the top of the square and the lower numbers are at the bottom which also helps with understanding the value of numbers.
    • Use an abacus for additions/subtractions instead of written methods. I’ve done this with Y6 children who had no concept of place value and it made a huge difference!
  • When moving on to column addition and subtraction, colour-code the numbers in each column with a known sequence of colours (eg Red White and Blue so they do red units first, then white tens, then blue hundreds). Put the numbers either on coloured card – or even better use painted wooden numbers so she can pick them up and feel the shape of each number
  • People with dyslexia tend to think in pictures, so when finally moving onto pen and paper calculations, try putting pictures of Strictly Come Dancing / X-Factor judges at the top of each column. The judges always sit in the same order on the shows, so it’s easy to picture them sitting in a row – then you know that you always have to add Bruno Tonioli’s numbers first!

One final tip I picked up at a session on dyscalculia to help children with sequencing numbers was to give them something associated with each number so that they have something to relate that number to – seeing how the number matches the object and handling the objects while they count makes it more of a multi-sensory experience.  For example if you want them to count in 6s, rather than giving them something generic like pictures of 6 spots or sets of 6 cubes, give them egg-boxes.