Jo Boaler is one of my go to people for insight into best practices in math education. Educated in England, she is now a professor at Stanford University and supports a site called You Cubed that has high quality resources for K – 12 educators. I participated in her online course on Fractions, an area of mathematics that causes many students and teachers consternation. What I like about Jo is her focus on conceptural understanding and number sense over memorization.
The following paper is worth a read:
Here is a 15 minute video in which Jo Boaler discusses “Number Talks”, which is a practice that helps students develop number sense.