Thanks for reporting on these experiments. I only knew of the 8 year study, previously. Most significant about the Williams experiment, for me...the worst boys as we know today are the boys with the highest level of unresolved trauma. I have 5 children, and we all have unresolved trauma. We have enormous pressure from outside influence, and I have no means to pursue the children's interest. So, are gains are small in comparison to this experiment. So yes, the mixed ages, the lack of pressure, and means to pursue interests are the keys. Our public schools have between 30 and 40% children with trauma, in TN. Now, with expanded definition of trauma including shaming and criticism, the numbers would be much higher. And I imagine in inner city schools the numbers are sky high. I am fully convinced that even small slots of time devoted to Self Directed education would help children to heal. I am working on games toward that end. What can be done in the 15 or 20 minutes a teacher can spare? Just discovered this blog. Phenomenal work! I am grateful to you, Dr. Gray.