Anyway... Here is the book:
The newest version is $60... but you can get older versions for a lot cheaper! The newest version comes with a DVD (maybe the older ones do too?) which really helped me to understand how to facilitate a Number Talk.
So the idea is that you, the teacher, facilitate a discussion with your students about math. The key to facilitating this is to give your students the language to use during a Number Talk and then to back off and let them discuss. Teach students the framework of a Number Talk, including hand signals!
Hand Signals that I use:
I'm still thinking about the math = fist by their heart
I have an answer = thumbs up by their heart
I have more than one strategy = hold up fingers by their heart
I got the same answer (me too) = this is ASL for 'me too', make your hand into a "Y" and move it from your chest outwards
Teach students the phrases you want them to use including vocabulary: solve, sum, difference, addend, count on, count all,
Teach students the names of tools and strategies that will help them to get to the answer. At a 1st grade level, many of my students worked hard to solve it in their head by the end of the year, but during the year, we learned how to use and later visualize tools like a ten-frame, rekenrek, abacus, counters, etc.
Topics can range from numbers/numerals, number identification, addition, subtraction, patterns, or anything else you might want to focus on in math (reminder, I teach first grade, so my experience is doing Number Talks at a lower-el level, but you can absolutely do these with any grade). This book actually gives you ideas for LOTS of Number Talks with your grade level, which I think is so helpful.
So.. here is a video that might help you to see what a Number Talk might look like:
This video is a little quiet, but it does a really nice job of showing a Number Talk.
Here is another good video from YouTube:
At the start of my school year, depending on my students, I will start by showing them 5-frames or 10-frames and asking them to subitize the dots. My goal will be for them to use strategies besides counting all.
Once my school year gets rolling, I will write more about Number Talks and add some video from my own classroom.
Feel free to comment with questions or remarks about Number Talks!!