Professor Tidball is an excellent teacher. He is able to explain things in a clear, coherent lecture, and makes sure everyone understands. He handwrites his notes on the whiteboard (thank god for no powerpoints!) which gives you plenty of time to copy them down. For 155 his tests are not multiple choice, but are very straightforward, certainly a welcome change from the 111 series. In addition to all of this, he is a very nice guy who is always willing to help if you have any trouble!