Hell, I don't think anyone really understands fractions until they've taken Elementary Set Theory and constructed the reals, and I don't think anyone really und

Hell, I don't think anyone really understands fractions until they've taken Elementary Set Theory and constructed the reals, and I don't think anyone really understands high-school trig until they've taken real analysis, etc. It's a great feeling to come back to the "simple" topics from early in school, and to realize how much rich knowledge they communicate, and the level of detail that really sits underneath them.