Multiplying by 10/100

So it’s another new year and Block A comes round again. My year 5’s were looking at what happens when you multiply and divide by 10 or 100. I had used the Moving digits ITP and they were displaying answers on mini whiteboards. They seemed to be getting it fairly well apart from when there was a zero in the original number and also dividing a units digit by 10. There were various errors which persisted despite many examples and explanations.

A second lesson didn’t really improve matters. Several children were just leaving the units digit out when dividing a HTU number by 10 and there were other children who were either omitting zeros or inserting them randomly.

Over the weekend I tried to think about how I could show this in a different way to improve their understanding. The ITP wasn’t working as a visual image. I did wonder about having the children being a human number and getting them to hold hands as they moved up and down the number line but wasn’t sure about how well this would go down with my year 5 boys. Then I remembered a resource from Tes many years ago.

http://www.mathagonyaunt.co.uk/INTERACTIVE/mult_divide/mult_div_lorry.html

This shows a number on a lorry that goes up and down a hill with a belisha beacon as the decimal point. I used it today with my group and hey presto! Lots of excited gasps of “I get it now!” The visual image of the lorry seemed to make much more of an impact than the moving digits ITP.

The children felt much more confident about their understanding of this concept after using this resource.

I was really pleased that I had been able to find something that helped so much. It reminded me again how important good visual images are for so many children.

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One thought on “Multiplying by 10/100

  1. duckiec

    Am following your blog with interest WW, as I begin my MaST in a very few weeks.

    I just love the mathagony resource and wish that I’d had it during that first week back – I did have children holding hands to demonstrate that the digits cannot be separated – like a chain that a decimal point doesn’t break (single gender groups of children though) – but I know that I didn’t get through to one or two.

    Thanks again for the link.

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