You can learn more about the US Constitution at Hillsdale College.
They offer FREE online courses on many topics, including the Constitution. Check out the possibiities at the link below.
Hillsdale College also offers a FREE 1776 Curriculum: American History and Civics Lessons for K-12 Classrooms.
You can learn more and download the complete curriculum at the following link:
https://k12.hillsdale.edu/Curriculum/The-Hillsdale-1776-Curriculum