Do your quarter grades count for colleges (especially the privates and Ivy Leagues)?

Colleges count whatever grades appear on your transcript, because those are the grades they see. You need to find out if your school puts quarter grades on your transcript or not.

here in NYC the most important is the average by junior year it must be over 85, if you want to get into a good college, plus reagents and SAT scores i doubt there is much difference between states in this part you can slack off in senior year

some schools use semesters, and other schools only go about 10weeks and follow the quarter system so it's quicker. It really depends on the university, i'd say more use the semester time periods and I like this more, quarter system seems too much work crammed into a smaller amount of time. Colleges really only look at your final grade in high school, they don't go looking at even mid-term grades, stuff like SAT scores, and overall GPA is more what they're looking at here.