The TMC Pro area is full of teaching and activity books arranged by discipline.
Listed below is a small sampling of keywords that can be used generally or in combination with a discipline (Science, Math, Language Arts, Etc) to start a search:
Example Subject Headings:
It's good to remember that the TMC is not the only place where you can find materials helpful for K-12 teachers.
Each discipline will have a section on instruction so make sure you check beyond the TMC stacks!