Numicon Subtractions - Blackout Cover

[deanstreet]

I see there is this thing called Numicon Subtraction Cover to black-out the Subtrahend (say 2) in 6 - 2 = 4.

Where can I buy one?

You can download them free here and print them out. https://fdslive.oup.com/www.oup.com/oxed/primary/maths/numicon/Numicon_pcms_subtraction_covers.pdf?region=uk (that took me seconds to google)

However, why wouldn't you put the 2 piece on top of the 6 piece to show the difference is 4?

@toomuchicecream putting a piece on top of another piece is a bit difficult to see the result, especially when my child is just starting subtractions.

In that case, I wouldn't be teaching it as subtraction. I'd be teaching it as composition of number. One of Gelman & Gelistel's (sp) later principles of counting is heirachical inclusion - the idea that inside every number lots of other numbers are hiding. So I'd be talking about how many ways can I split 6 up into other numbers. Starting with 6 counters or other objects and seeing how many different ways I can split them on to 2 plates. Then hiding some of the counters under a cup and asking the child to look at the ones they can see and tell me how many are hiding. Once they've got a solid grasp of this, I'd then introduce the written equations to show that 6 is made of 4 and 2, 4 and 2 make 6, and we can write it 2 + 4 = 6 or 6 - 2 = 4 etc. Then putting Numicon pieces on top of each other won't be as abstract and therefore difficult.

The skills progressions that you can download and print out here: https://www.ncetm.org.uk/in-the-classroom/early-years/ have really good, step by step ideas how to develop this understanding with your child.

Number bonds are something I plan to teach next after subtractions. I think it is easier to teach sequentially.