"The most useful piece of learning for the uses of life is to unlearn what is untrue." -Antisthenes As many of you know, in addition to news about cosmology, space, astronomy, and physics, I'm also heavily involved in education. This includes, in various stages, teaching, curriculum design, and mentoring students. But I got the following message from Rita from the UK last week -- who's about to start her A-levels -- and I felt slightly ashamed. (Message edited slightly for clarity.)