For those whose memories of learning science at school consist of burning magnesium and playing with iron filings and a magnet, and whose brains shut down as soon as things start to sound 'too technical', I Used to Know That: General Science is here to remind you of everything you've forgotten or should have learned. You may not be studying for an exam any more, but an understanding of basic scientific principles is essential in everyday life, from choosing which vitamins to take to deciding on the best way of heating your home. Written to O Level standard, this accessible and informative guide will fill in any embarrassing gaps in your knowledge, providing you with a solid understanding of biology, chemistry and physics. For those who enjoyed science at school, this is a welcome trip down memory lane. For those who didn't, this book will show you what you've been missing.