(no subject)

My high school chemistry teacher (hello, Mr Kirk!) would be so proud. I was watching this week's Psych, set in a school for gifted kids, and when one of them wrote something on the board I immediately recognised it as being the Avogadro constant despite the fact a) it's almost 25 years since I did A Level Chemistry and b) I was crap at the subject even then so there is no chance I can remember now what it's actually for.