After watching this video of the weird and wonderful James May's LEGO project:
We thought we'd investigate.
The first time i'd done this, I asked "how many bricks will it take?"
The second time I asked "How much would it cost?"
This time the problem was "Pretend I've got 300 grand. Can I afford to do it?"
This last question was infinitely more engaging than the first two. No real difference to the second one mathematically, but way superior in getting the guys hooked.
We decided we'd just build the "shell" of a house - i.e. four wall and a roof.
The kids asked all the right questions:
how much is LEGO?
how big is the house?
how big is a lego brick?
We travelled to the LEGO site and saw a box of 221 bricks for £10.
I happen to have some lego in the classroom anyway, so some kids measured the different bricks and decided the average measurements were 5cmx3cmx2cm.
The rest of the kids measured the room (7mx7mx3m) and decided the house would have 4 rooms down, 4 rooms up, so said each panel would need to be at least 14m x 6m with a 14mx14m roof.
There was some discussion about how thick the walls would need to be (would it just be one row of bricks, or several? should they be hollow or solid?) and we settled on solid walls, 40cm thick.
And we were off.
A few interesting different approaches - I'd worked out how many bricks were needed by fitting them along the measurements (so think for 14m along, would need 280 bricks etc), which is the route many groups took. A couple spotted a shortcut (that i have to admit i hadn't even considered - well played guys) and simply found the total volume of the walls and roof, and divided this by the volume of one brick. Love it when they get one over on me!
The kids were delighted to find that i'd be about £20,000 over budget, mocked me (although some very kindly offered to let me have their old lego) before one astute young lady pointed out that i'd probably want windows in the place, so if you subtract the legos for the windows, i'd come in just under budget - cheers L___!