I would suggest
Lower-Primary - Start as Age 4 - Pre-K, K,Grade 1, Grade 2
Upper-Primary - Start at Age 8 - Grade 3,4,5,6
Lower Secondary School - Start at Age 12 - Grade 7,8,9,10 +Point All the human Biology stuff can be left till Grade 7 instead of introducing in Grade 6.
Upper Secondary School/Vocational School - Start at Age 16 - Grade 11,12,13,14. 50% of the time has to be in internships/apprenticeships/AP classes in High School. 50% in life skills + Point Students are old enough legally to drive and work part time when in high school. No division between upperclassmen who can drive and lowerclass men who cant. Also there can be specialized schools like Sports schools, Carpentry school etc. All schools would share life skills part of the curriculum but the rest would be specific to a school.
College - 3 year college. Even now the first year of college is spent catching up on stuff which really should be taught in high school. +Point People are 20 by the time they go away to college and a bit more mature and don't freak out too much at college. Also make the age to drink 20. People at college will drink. Encourage respect for the law by not having laws that will be flouted.
Age to work part time, age to Drive , age of consent 16. Basically when you come to the new High school (Grade 10) you get to fuck,drive and work.
Also make the age to vote, age to drink , age to enlist 20. When you come to college you get to vote, drink and fight.