Thursday was the first day of classes at Hamilton Elementary, which is among schools in Wisconsin that have a year-round academic calendar.
Principal Steve Michaels says Hamilton operates on a 45-15 schedule. The quarters are roughly 45 days long with 15 days off in between.
The year-round curriculum is aimed at preventing what educators call the "summer slide" - the learning loss that students experience when away from the classroom for the summer months.
Michaels tells Wisconsin Public Radio News that before switching to a year-round calendar, teachers spent most of the first quarter re-teaching material.
In Wisconsin, Milwaukee has 13 year-round schools with others in Racine and La Crosse.