School systems handle the challenges of diverse student populations in different ways. Some countries have non-selective and comprehensive school systems that seek to provide all students with similar opportunities, leaving it to individual schools and teachers to meet the particular needs of every student. Other countries group students, whether in different schools or in different classes within schools, with the aim of serving students according to their particular academic potential, interests and/or behaviour. Having underperforming students repeat grades or transferring struggling or disruptive students to other schools are two common policies used to group students for this reason...