I love professor Gehret. His lectures are super organized and clear. I would definitely recommend taking 115A with Gehret if this is your first proof class. His homework can be sometimes challenging but it covers every topic he talked in class. And my TA Jaehoon Lee is so far the best math TA I've had. They both put a lot of efforts into teaching and they care about how well their students are doing in the class. Most people did not like 115A that much, but Professor Gehret made it great. His tests are fair too.