Some high schools choose block scheduling because this schedule gives teachers more time for individualized instruction, students have time to complete longer cooperative learning activities and students have less information to process from the school day, giving them more time for reflection. A block schedule has three or four longer classes rather than the traditional seven or eight period school day.
Block scheduling has three common forms. Students attend classes for longer periods every other day on the alternate day schedule. The 4x4 semester plan has students attend four 90-minute classes every day for four quarters, and the trimester plan has students take two or three courses for 60 days.
Block scheduling also has cons. If a student misses a day of class on a block schedule, he misses the equivalent of two or three days of instruction and may have trouble making up the work. Some teachers choose to lecture during the 90-minute class period rather than engaging students in active learning activities, and students may have trouble paying attention for that long.
Critics claim that students benefit from daily exposure to music, mathematics and foreign languages, and students may suffer from retention problems in these subjects. Teachers have trouble covering the subject matter for Advanced Placement courses in 4x4 and trimester block schedules, but some schools have remedied this problem by requiring students to sign up for two Advanced Placement courses and attending both courses all year.