Have you seen the Mindset Kit? http://www.mindsetkit.org
It's a free professional development website created for educators and parents.
In addition to her reserch and preparing new math teachers, Jo Boaler runs a Stanford University website called youcubed that has a great deal of information for teachers, parents, and educators. Click Learn More below. I recommend her book too - I loved it and gave it a great rating on Amazon. Her online self-paced class (for parents too!) sounds so interesting.. In Chapter six, she gives some advice on grading where suggests trying a 4 point scale and it will be very easy to implement.