I was watching this video about a school that found chalkboards from 1917 during a recent renovation. This 'multiplication wheel' (as described by the principal) was shown, but I can't figure out how it was meant to teach multiplication. Most of the techniques that I saw on the internet use numbers in sequential order, and each times table is in a separate circle, rather than this one where they all seem to share one circle. Can anyone explain how this teaching tool worked?
I was taught tested using something similar in the mid 70s. The basic idea was that you were suppose to memorize the tables from 1 to 12 and the teacher would call your name, and work her way around the wheel. If you were reciting 9's table and she in turn pointed to 5, 3, 11, 6... you would be expected to say "45, 27, 99, 54..." The numbers were in random order to encourage memorization, not sequential addition.
The only difference I see is that the numbers around the circle are sometimes repeated, something I do not remember doing. EDIT: Also, there's no "1" or "10" on the circle, which of course are easy questions for anyone familiar with base-10.
