What is it?
I’ve used the “Incredible Hand Calculator” to demonstrate one method for learning/visualising/remembering the nine times table.
There are two sections – the demo section explains the method for 3 x 9, then shows further examples where the tens and units digits are calculated for the students.
In the practice section the students just see the question with the pictures of the hands, they can then work out the answer and click a link to check it.
The explain how this works link just links to the demo, it doesn’t explain how the method works. Students can work that out for themselves using the patterns in the nine times table.
I was working on some demos for alternative methods for the nine times table, but I decided that it was better to ask students how they calculate the nine times table, then get them to demonstrate and explain their own methods.
Can I download the activity?
Of course you can, but this one isn’t a single file, it’s a collection of web pages, so you will need to download a zipped folder and extract the files.
Once you’ve done that, you can start the activity by opening the page called index.htm.
The index.htm file does contain a small script, which may alert your web browser’s security settings, but the script simply pre-loads the images to make everything run a bit more smoothly.
The Incredible Hand Calculator – zipped folder
(Use this one with MS Windows built-in zip/unzip function. Once you’ve downloaded it, right click on the folder, then choose Extract All.)
The Incredible Hand Calculator – 7 zip
Can I adapt the activity?
Yes, it’s covered by a Creative Commons licence:
The Incredible Hand Calculator (including the images) by Lois Lindemann is licensed under a Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales License.