Students who misunderstand some important point in mathematics will find that they can identify with a student who is at the blackboard and has made a similar mistake and can, in effect, get individual attention without monopolising the teacher's time. Asian teachers often complain about class sizes getting too small to find a useful range of student solutions to a problem in order to conduct a good class, instead of complaining that the class is too large to teach effectively, as in the United Slates. It applies a learner-centred approach that places considerable emphasis on student self-assessment, in which students are expected to take an active role in designing their own learning activities and work collaboratively in teams on projects that cut across traditional subject or disciplinary areas. By the time students enrol in upper secondary school (grades 10-12), they are expected to be able to take sufficient charge of their own learning to be able to design their own individual programme where, without a grade structure, each student proceeds at his or her own pace within the modular design of the system.