Test your powers of observation by looking at these two pictures. If you can see them that’s a start. Now look more carefully.

Somewhere in these two pictures there are certain differences. If you look hard you may spot them. Write them down and time yourself.

Less than three minutes: very bright indeed. Less than ten minutes: jolly clever. Less than one hour: still jolly clever, though perhaps not quite up to scholarship standard, (but who cares about silly old scholarships, anyway!). Over four hours: well done! Even quite good atom scientists were slow starters. Ten to twelve days: a very good try indeed! Over four months: keep at it! Four months to one year: you’re doing well!