Mathematics

Mathematics is the subject people most often say they are bad at, usually meaning they were taught it quickly and never told what it was for. This category takes the opposite approach: the constants and theorems worth knowing, the vocabulary that gets used loosely in everyday speech, and the historical moments when a genuinely new idea arrived, zero among them. Nothing here requires calculation under pressure. The explanations concentrate on what a rule means and why it holds, because almost every piece of school mathematics is a short idea buried under notation.