SEa period of time in a school day when a student does not have a class 〔学校里的〕自由课，自习课，空课时
Examples from the Corpus
free period• Robert always had a free period after lunch.• I spent most evenings and every free period from college by your bedside.• More important, however, is the occasional presence of an initial relatively symptom free period, which can mislead the clinician.• This symptom free period lasted for several days and even weeks.• Can you take 2H in your free period after lunch?