Collaborative learning tasks may represent an effective way to stimulate higher-order processes among high-ability students in regular classrooms. This study investigated
the effects of task structure and group composition on the elaboration and metacognitive activities of 11th grade preuniversity students during a collaborative learning task: 102 students worked in small groups. On an ill-structured or moderately structured task. Differential effects for
cognitive ability were investigated using a continuous measure. Likewise, the effects of group composition were examined using a continuous measure of the cognitive
heterogeneity of the group. The group dialogues were transcribed and coded. Analysis revealed an interaction effect between task structure and cognitive ability
on students’ elaboration and metacognitive activities. Task structure had a negative effect on the elaborative contributions of high-ability students. For students with lower abilities, task structure had a positive effect on
elaboration and metacognitive activities. No effects were found of the cognitive heterogeneity of the group. Group composition seemed not to be related to group interaction
among 11th grade pre-university students. The results indicate that open-ended collaborative tasks with little guidance and directions on how to handle them, can
stimulate higher-order processes among high-ability students and may offer them the challenge they need.