My old school district (~8 years ago) actually had all PK-K, 1-2, 3-5, 6-8 & 9-12 grade breakdown, but they noticed that during the 6-8th years, the students grades bottom out, sharp declined in test scores and huge rise in bullying had occurred and huge teacher turnover and difficulties attracting teachers to teach the middle school grades... So, the school district decided to phase out 6-8th grades and instead of 4 different grades school, they ended up with 8 K-8th school, they are now able to have smaller class sizes, combined the resources and better allocate the money to serve everyone and I stayed the 1st year and it seemed like this K-8th model was working . However, I left to go back to a 6-8th grade model and sometimes I wished I had stayed at the old school district.