Last week was lesson observation week (LOW). This means that teachers visit other classes. I visited a maths class and a chemistry class. The maths class were doing logs which reminded me about one of the questions on the mock exam I gave to my SL students. It was last years time zone 2 paper, the question I'm concerned about is 4d (iv).

If the fractional change in energy when a neutron collides with moderator nucleus is 0.3 estimate how many collisions it takes to change the energy be a factor of 10⁶ ?

So if the number of collisions is n 0.3ⁿ = 10^-6

nlog0.3 = -6

n = -6/log0.3 = 11.47 approx 12

I think this is a bit tough for standard level.

Back to the chemistry class. The class were doing a practical so Ashok thought it would be more interesting if I took part. The experiment was to find the amount of asprin in a tablet. I had no idea about the chemistry behind the experiment but it was fun to do it anyway. Very reminiscent of the sort of thing I did when I was at school.