I'm doing some revision tutorials for students at the moment, with finals looming next week. The look of panic on their faces makes me feel empathetically nervous. They hold themselves as if they fear moving too quickly, in case knowledge spills out of their brains like water from a carelessly held glass. I vividly remember that feeling. During my finals, I stopped watching factual programmes on TV to prevent vital information about mating systems in birds being displaced by the date of the Battle of Bosworth, or the properties of quarks.

One really nice thing about doing revision tutorials — if you can weather the waves of panic — is that you can make a tangible difference. For better or worse, the material often only starts to come together during revision. Students are often struggling to see how a and b fit together, and with a few simple explanations you can give them an overview. The almost visible lightbulbs that appear over their heads at these moments make it all worthwhile.