In Florida, if the school includes 6th-8th grade they are eligible to play HS ball (without losing eligibility).
Technically you can actually play 7 years for varsity HS. In general though it only happens at high schools with very marginal teams, although there are some clear exceptions.
They actually ended up adding in rules that you could only play 1 year per grade of middle school (to stop some idiot parents in boys football and basketball who were keeping their kids in 8th grade an extra year so they weren't using up their HS year eligibility).
Technically you can actually play 7 years for varsity HS. In general though it only happens at high schools with very marginal teams, although there are some clear exceptions.
They actually ended up adding in rules that you could only play 1 year per grade of middle school (to stop some idiot parents in boys football and basketball who were keeping their kids in 8th grade an extra year so they weren't using up their HS year eligibility).