Plenty of technical classes require students to know a thing or two about LaTex. It is a wonderful document preparation system that lets you display complex formulas. Thanks to WP QuickLaTeX, you can display all kinds of equations in your posts. It takes care of numbering displayed equations automatically and supports TikZ and pgfplots packages.
This plugin requires no additional installation to work. You can place math expressions in your text and use the latexpage shortcode to have them converted into images, embedded in your posts, and cached. You can change font size, color, background color, caching, other settings in the back-end.
WP QuickLaTeX lets you cut and paste expressions directly into your posts, pages, and comments. You can download it for free.