We have used Calvert's program since Pre-K. I love that it comes with everything you need in a box, we live in a remote area and this makes things easeir for us. We also love the flexibility Calvert offers, and the fact that I can contact a teacher any time I need a little extra help, or a different approach.
I have another daughter who graduated from Calvert and is now doing an online high school program. We thought about moving my younger daughter to this other program, but her sister says that Calvert's program has her so far ahead of the other kids that she recommends (to her sister!) that she stay with Calvert. She feels that Calvert's writing and Math have given her an advantage over other kids in her current program.
I don't think you can get a better recommendation than that!
For me, it is the flexibililty and the resources ON TOP of their outstanding curriculum, that keeps us a Calvert family.

We used Calvert's 6th Grade Interactive program last year. My daughter LOVED it, especially the classes. We are disappointed that the actual "interactive" part is changing (no more actual class time). We were very pleased with the curriculum, support and the online activities. She liked the Brain POP website and is looking forward to using it this year. I think she's looking forward to the clubs most this coming year. Can't wait for high school classes to be availble!