How the publisher describes it:
“The Numdrum was invented by John Harrison to help a child struggling with the basics of understanding numbers, adding and subtraction. It is a simple but revolutionary development, which through its design addresses the serious inadequacies of some present teaching aids, most notably the number square.”
Review by John Leversedge
“I am still finding ways of using the Numdrum myself”
I have been teaching for over a quarter of a century and I have seen a lot of ‘whiz’ educational ideas and the number that have failed to live up to exaggerated promises have left me rather sceptical. Nevertheless, I looked forward to seeing if the class set of Numdrums would be a useful tool in the classroom. At the time, I had a mixed y5 class that included children with severe limitations in arithmetic. I was certainly encouraged by the initial response: you can’t put a Numdrum in front of a child without him/her wanting to pick it up and ‘play’ with it. Number lines, squares, even the interactive whiteboard do not have that wonderful, child-friendly tactile appeal. The first time the pupils used the Numdrums they spent the time manipulating them, imagining and describing many ways they could be used. I challenged them to tell me four different things about the Numdrum; I stopped them after 10!
Over the next couple of terms and several sessions the pupils and I discovered different ideas we could explore with the Numdrums and different ways of working with them. After a while I found I was using them in two main ways. One way was as the whole class mental maths starter. We would look at such things as patterns (using coloured white-board markers directly onto the Numdrum - very effective and they wipe off easily), multiplication tables, serial additions and subtractions. Using the clear sleeve marked with two appropriately spaced windows the pupils would quickly recognise, for instance, patterns of units and tens in the eight times table, or the addition/subtraction of eight to 43, 53, 103, etc. Once the patterns were becoming established and I wished to develop speed through practice and competition, I noticed that by allowing the less fluent to continue to use the Numdrums they could find answers at a similar speed to the more able mental mathematicians: I had found a way of facilitating differentiation during mental maths starters.
I also used the Numdrums to support my very low ability group who were having great difficulty adding and subtracting single-digit numbers; particularly, of course, when crossing 10s. I realised that they had not then internalised a continuous mental number line but, rather like the traditional 100 number square, it was fragmented. They could manage moving horizontally across the number square but the vertical jumps were problematic. I found that after a few lessons using the Numdrums these pupils were crossing 10s confidently and were also transferring this skill to their mental number line.
The Numdrum is not just a device for increasing variety and maintaining interest within the classroom. It helps to develop and consolidate concepts and establish number patterns that give mathematics its meaning. I found with my y5 class that all of the pupils enjoyed and benefited from the opportunities for using the Numdrums, though, in particular, the lower ability pupils achieved the more dramatic progress. But then, I am still finding ways of using the Numdrum myself.