Hi Mary Ellen,
Before I can answer, I have a few clarifying questions.
1. I assume by IT, you mean infant and toddler, yes?
2. When you say elements of CLASS, do you mean the dimensions and domains? The foundation of the framework? Something else?
3. For school readiness, do you mean long term outcomes?
Essentially, I think your question is: Are there studies that show that children who are in settings with higher scores on Infant and/or Toddler CLASS are more likely to be ready for school (pre-k / k)?
Please let me know if my assumption is correct and then I can guide you to some references.
Thanks, Vicki