I found Word's equation editor (2007 onwards, not the crippled MathType before) very good for real-time typing of math in class. It's quite close to LaTeX when it comes to symbols, smart enough to use / for fractions or convert ² to a superscript 2, etc. and generally requires far fewer braces because spaces or operators are used to separate tokens, e.g. a^15+4 yields 𝑎¹⁵ + 4 because it makes more sense than 𝑎¹ 5 + 4 (what LaTeX would make of it). It also features WYSIWYG build-up of the equation as you type.