A maths lesson...
... no, no – don’t just click on the next blog on your bloglines – it’s all fibry (hmm – that’s one of those times when the American spelling works better – fibery), I promise!
So today I taught my Lower 6th groups (aged 16-17) about composite functions. Mathematically speaking a function is like a number machine where you put a number in and get another number out. A composite function is one where you do this twice (or more than twice).
So (and yes, this is a bit mathsy, bear with me – nod and smile if necessary – the fibre is coming… ) if I have a function (number machine) that I call f – say it adds 2 to every number I put into it, then I would say f(x) = x+2. And if I have another function (number machine) that I call g, and g multiplies every number by 3, then g(x) = 3x. If I put a number (let’s say 5) through f first, then I get 5+2 = 7. If I then put this result through g, I get 3×7 = 21. And I call it gf(x) because it’s g of f of x.
And by now you’ll be splitting into two camps – there will be those of you muttering that it’s slightly insulting that I’m going so slowly, and those whose eyes are starting to glaze over.
Here’s the fibre:
If I put FIBRE
through the function SPINNING
I get the result YARN
If I then put the YARN
through the function KNITTING
I get a SHAWL
So if Spinning is S(x) and Knitting is K(x) then KS(fibre)=Shawl
It’s a good analogy, and they liked it – and it meant I got to play with fibre IN THE CLASSROOM!! 
nine comments:
Awesome! Maths and fibre go so well together don’t they
Diane () (link) - 27 June '07 - 11:04
Brilliant! I love this. You’ll have em all knitting and spinning yet!Big Ruth () - 27 June '07 - 14:08
Oooohhh, you very nearly lost me there! Once you used the fibers, though, it all became crystal clear. (I’m a historian by training and a history textbook editor by profession. Though I’m surrounded by math editors, they’ve never made it as clear to me as you have. Perhaps you should get into the textbook industry…!
Tracy WW () (link) - 27 June '07 - 17:34
Oh, that’s clever! Clever example, clever sneaking of fibery goodness into classroom.Carrie K () (link) - 27 June '07 - 20:06
Very cool!jessica () (link) - 27 June '07 - 20:37
I get it!!!Daisy () (link) - 27 June '07 - 23:09
I stayed with you. Clever woman!jessie () (link) - 29 June '07 - 18:56
My hubby does maths. I’ve always maintained anything beyond what you need, (ie. -, +, etc.) is pointless, letters and numbers should never be mixed. You’ve made it all come clear, even before you added the goodness of fibre! (But don’t tell the hubby that… x
Louise () (link) - 01 July '07 - 14:27
I know this comment is completely off topic, but a dear friend has just become a grandmother. Her daughter, son-in-law and granddaughter are living in Cambridge for a few years. Susan, my friend, and her husband, Dick, will be visiting starting this weekend, and staying for 3 weeks, I think. She is trying to find out about local yarn shops in the Cambridge vicinity. There’s always knitting to be done for a first grandchild! Could you, or anyone else, please help?Many thanks.
Dee near Berkeley (California)
Dee near Berkeley () - 02 July '07 - 16:48
