Teaching mathematical logic
I taught two courses this year that I haven't taught before. One of them was our 4th-year undergraduate course on mathematical logic, "Logic, Computability, and Incompleteness". As usual, I ended up writing my own textbook. Here it is as PDF and here as HTML.
Why yet another textbook? Two reasons mainly. One is that many existing textbooks are addressed at maths students. This shows up not only in the examples and illustrations, but also in the fact that comparatively little time is spent motivating, explaining, and discussing definitions, proof ideas, or results. I wanted more of that.