It also features individual accountability, which means that team success depends on individual learning, not group products. Curriculum has to be thought of as both catering to significant individual differences and being able to stretch each learner to just beyond his or her self-defined capacity (Dumont, Istance and Benavides, 2010). However, given the cross-country variation in who has responsibility for curricula, it is difficult to provide clear policy direction on curricula at the school level. Co-operative learning methods, which involve the teacher placing students within the same class in small, temporary groups with mixed abilities focusing on tasks that require them to rely on each other's skills, tend to work equally well for all types of students (Slavin, 2010).