Number talks are discussions about a particular problem that has been crafted in such a way that key foundational ideas of mathematics can be evaluated and demonstrated. The teacher acts as a guide, not the master, asking students to clarify their thinking, consider and test strategies, investigate and apply relationships, and learn that making mistakes and taking risks can and does lead to success.
The resources below were from discussions in 2014 and 2015 of Number Talks: Helping Children Build Mental Math and Computation Strategies, Grades K-5 by Sherry Parrish.
Presentation on Number Talks Chapters 1-4