median
don steward
mathematics teaching 10 ~ 16

## Saturday, 1 October 2011

### equivalent ratios

introduced to me by Dave Hewitt

“Alan, you can be the 5 × table”
“Beth, you can be the 8 × table”
teacher:
“I say, … 2”,
points to Alan (who should say 10)
then to Beth (who should say 16) etc.,
continue with this, for a while: the teacher saying a number and the two students giving their particular multiples of this chosen number

then the teacher points at A and ask them to give a number (looking puzzled if they say any number not in the 5 times table and maybe reminding them which times table they are)
Alan says “40”
point at yourself and ask the class “what will I say?” or just gesture
then do the same starting with Beth (who should give a number that is a multiple of 8) etc.

after a while point at A, who says a number (e.g. 55)
then point at yourself and gesture that they should be silent about your number (think 11 but don't say it)
then point at B, questioning “what will she say?” (88) etc.
then do the same, pointing at B first

then maybe change the times tables, and the students

then maybe write down a few examples of the A then corresponding B numbers e.g. 55 : 88