18/6/2010

Kevin Costner, Saviour of the Gulf! – Um, not so much…

Filed under: — Bravus @ 1:03 pm

So, here’s the news story: http://jalopnik.com/5565816/bp-purchases-32-of-kevin-costners-oil+water-separation-machines

And here are my back-of-the-envelope calculations:

It can clean up 200 gallons of water per minute, per machine. Any back-of-the-envelope calculations of the total volume of water in the Gulf, or even just the affected areas? Even if it were only a billion gallons, which is nothing (about 4.5 million cubic metres, or about 0.0045 cubic km), it would *still* take the 32 machines… about 17 years.

And, a little later:

Current surface area of the spill, about 6,500 sq km. Even if the affected water is only a metre deep that’s still 6.5 cubic km… 1444 times my estimate above.

Call it 24 and a half thousand years.

Thanks Kev.

There may be a solution – but not one that will avert devestation – but this sure ain’t it.

C’mon, teachers!

Filed under: — Bravus @ 9:11 am

I mentioned a few days ago that I have been answering people’s questions on Yahoo Answers.

Lots of students ask questions they’ve been asked, in tests or homework assignments. Quite a lot of these are in multiple choice format – and quite a lot of them are terrible. There are no correct options, or two or more, or they reinforce common student misconceptions, or…

Teachers are good and competent, generally, and trying to do the right thing. I blame the trend toward more multiple-choice questions for part of the problem – they don’t seem that hard to make, but it’s actually quite difficult to make really good quality ones.

Whatever it is, it’s a real worry when the assessment tasks don’t fairly assess the knowledge, and in fact may be ‘antieducational’ in confirming misconceptions.