Assessment is essential ... these two books are essential!
Asking the right questions is significant! These books are super resources for identifying good questions!
Instructional strategies are key! Using research-based strategies to develop strong lessons are necessary!
For enrichment and mathematical background information I love to read Theoni Pappas!
Since writing is an initiative in our school, I dug through my shelf to find an old book, Mathematics Write Now. It emphasizes creative writing in math. I also stopped by our school's professional library to check out Algebra Out Loud which has ideas for communicating math that could be written!
Last, for inspiration, I read Teaching with Heart: Poetry that Speaks to the Courage to Teach by Intrator and Scribner.
There are so many more books I could share but these are books I value today!