## Thursday, 30 July 2009

### Carnival Of Maths 55 (i think...)

Well to be fair this isn't mine, my old economics teacher showed it to me, but i've never seen an activity that works for pretty much every kid (and i teach abilities ranging from 16 year olds who can't tell the time to 11year olds who are happy solving quadratics) it's called Lobsters. Basically, split your class into teams tell them they run a lobster fishing business for the day. Options are simple-they start with 6 lobster pots, which they can choose to put in the shallow area or the deep area (or split between eg 5 shallow, 1deep). Simples, eh? If it's good weather, anything in shallow gets u £2, anything in deep gets u £5. No brainer, right, bung em all in deep! But if it's bad weather, anything in deep gets destroyed so they get no money for it (plus they lose that pot). Demand and supply dictates that anything in shallow now will be worth more-£6. Weather forecast says a 1/3 chance of bad weather, we decide this by rolling a die after the teams have placed their pots for the day. At any time during the game teams can buy more pots at £3 each. That's the game, kids r responsible for keeping their own accounts and r fined if they make banking errors, winners are the ones who make most profit. Some teams play it safe, some teams blow their budget buying loads of pots some go for a high risk strategy (with brighter kids i tend to offer a loan at a Rate of 10%per day). Try it, it is superb. Cheers mr Jervis!

Right, that was like the bag of Doritos u sneak while waiting for the taxi, onto to main course!

Over at futility closet a blinding old puzzle called petals around the rose-i love this because for some reason my weaker students tend to crack it before the more able ones.

Dan kicks summer school off with a great idea for getting kids to understand why we name lines and points the way we do-i've already nicked this and used it when teaching loci!

Not a maths site by any means, but there's an idea waiting for a lesson at swoopo.com- begs ideas of break even points, and is an abject lesson for any poker player about not getting pot committed.

I don't know if this is cheating as the number warrior submitted this idea about applying probability to the math teachers at play carnival, but i loved it so it's going in here.

Slightly off topic, but from an education point of view this article in the ny times about soccer players struck home with me, deliberate practise indeed.

A fab article from freakonomics showing a relationship that initially seems counter intuitive.

This compass activity constructing Kenny from South Park is something kids in my school love doin (link now active!)

Project dragonfly is a great tool for making plan views and 3D visualisations of a home, but the presence of measurements makes it a great tool for working with area and perimeter.

The math hombre collects a few very good links to different kinds of math related media

This youtube vid begs all kinds of questions about rates of change as we see the world's fastest, well, everything!

SquareCircleZ has a good collection of math software but i've not explored it all yet.

And finally, this has very little basis in curriculum, but my kids dug the fact that a wombat has geometric doody.

Right, thanks for reading, hope I've not screwed it up too badly.

## Wednesday, 8 July 2009

### Bras Glorious Bras

Read a brilliant story the other day about the apparently famous Bra fence in Cardrona, NZ.

Apparently, people just keep leaving bras on it. weirdos.

After a little discussion related to how many we think there are (answer: 1,500 ish) we moved on to look at how this had happened. People started leaving them in December 1999 and they were taken down by the police (Boo!) in late 2006.

A basic discussion about rates followed (how many per year, month, week etc) and we figured that a rate of roughly 4 bras per week seemed sensible.

We then did a bit of sampling. In the pictures we estimated how long each section of fence was (they reckoned about the length of a radiator, so we measured this and it was about 2 metres).

So we figured that if we could count how many bras were in one section, we could use that to predict how long the fence was altogether.

After cracking this and making a couple of small scale models of the fence using sheets of A5 paper to represent a fence section (decorated with bras lovingly drawn by the kids) we looked at graphing it. I had started with the assumption that we'd make some data up and draw something like the graph on the left below, using the rate we'd calculated earlier. But many kids suggested it should look more like a curve, because as it has gotten more famous more people would leave bras (G.- "man if i was there i buy a bra just so i could leave it!") altought this was countered by S. who suggested that if she was short of bras, she could just pop over to Wanaka to help herself to some free undies. The burgeoning kleptomania of S. not withstanding, we figured G. was right and the rate would increase as more people heard about it (a little checking proved him correct - good man, this kid knows his celebrity)

So we got em to draw both and estimate how many bras there should be at a few points depending on the shape of the graph (each graph went up to 1500, and along from 1999 to 2006).

All in all a pretty varied lesson thanks to our very pecuilar friends in the Southern Hemisphere feeling the need to undress near a field.

God bless you New Zealand!