Tuesday, 17 March 2015

Balancing versus Inverse function machine

Had an interesting conversation today with my intern; she is teaching equation solving to a year 8 group that will be going on to the Higher tier at GCSE when they get there. She was going to teach them equation solving exclusively using function machines, with unknowns on both sides dealt with by moving them and then drawing the function machine when you have a single variable. I asked her to use a balancing method for at least part of the topic (basically use function machines in the first lesson and balancing in the second) because they will eventually need to be confident with balancing to do higher tier rearranging formulae. Got me thinking on two fronts:

1) Should we be worried about introducing balancing in Year 8 to support GCSE, or would it be OK to wait until next year, or even Year 10?

2) Can you approach rearranging formulae using a function machine? I have tried to visualise how it might work before but never been comfortable with it. Particularly can't see how you would rearrange for y in something like 3x - yx = 2y + 7 without balancing.

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