Multiplying and dividing by 10 and 100
This links very much to derived facts
Using chairs is a really effective way of teaching multiplying and dividing by 10 and 100.
Choose children to represent numbers which they hold up on a whiteboard. They have to sit on the correct chair and then all move one chair to the left to multiply by ten, or one chair to the right to divide by 10.
Multiply by 100 by moving two chairs to the left; explaining that you are multiplying by 10 and 10 again. Vice versa for dividing by 100.
I use this method in conjunction with sliding whiteboards, which are also fantastic!
I also use place value counters to show using multiplying by 10 and 100 in real examples - for instance, when you need to work out 3 x 40 then you can work out 3 x 4 x 10. I feel that this method really helps them understand the concept in a more visual way.
An example of how I teach this:
I wrote 8 x 4, 8 x 40, 8 x 0.4, 8 x 0.04 on the board and the children worked in ability groups on the one I gave to them. As an extension I got the ones who showed great understanding the challenge of showing 8 x 0.004 and even 8 x 0.0004 as they were really into it!! Scroll down for photos of their work.
Below are photos of some of the children's work from the lesson.
I created this IWB with the children during an input to again enforce work on derived facts.
It was funny as some of them drew the array for 9x6 but then for 9x60 were going to draw sixty rows across so this was good for explaining that the array stays the same you just change the place value counter.
