The hardest class I'm taking right now is one called ''Steel Structures'' (name translated), which is basically a lot of maths, thinking and physics. Gotta calculate all of a building's structure, every single column, beam, decking and etc. It can be a real pain in the ass and it's a long process to do too. You easily get lot in your calculations which has happened to me several times. I'm currently failing this class, but I can still manage to get my grades up. I at least passed my last exam.