I really enjoyed taking cryptocurrency with Professor Bloomfield. There are quite a few homeworks, and they are somewhat time consuming, but most of them are just getting a hang of using geth and the IDE Remix. You learn a lot about cryptocurrency and gain a very detailed understanding of the basics of Bitcoin, Ethereum, and other cryptocurrencies that are case studies for the class. If you want to take a class that is a bit of work, but you learn a lot, this is one of the most interesting CS electives that I have taken. Bloomfield puts in a lot of effort for this class, and it is very visible that he cares about giving the best experience to learn about cryptocurrency.