Tracking is separating students by what is assessed as academic ability into groups for all subjects[1] or certain classes and curriculum[2] within a school.[1][2] Track assignment is typically based on academic ability, other factors often influence placement. It may be referred to as streaming or phasing in some schools. In a tracking system, the entire school population is assigned to classes according to whether the students' overall achievement is above average, normal, or below average. Students attend academic classes only with students whose overall academic achievement is the same as their own. Tracking generally applies to comprehensive schools, while selective school systems assign the students to different schools.
Students with special educational needs may be tracked into a self-contained classroom or a separate special school, rather than being included in a mixed-ability class.