Teaching children to ask and answer questions is critically important if they are to engage in reasoned argumentation, problem-solving and learning. This study describes how teachers can be taught to challenge children's cognitive and metacognitive thinking during cooperative learning and the affect this has on children's discourse and follow-up performance on classroom-based reasoning and problem-solving tasks. The study involved two cohorts of teachers, the cooperative+questioning condition (n = 14) and the cooperative condition (n = 11) and two groups of students (3-4 person groups of mixed ability) from each teacher's class. The results show that the teachers in the cooperative+questioning condition used more challenging and scaffolding behaviours than the teachers in the cooperative condition. The study also shows that the children in the cooperative+questioning condition provided more elaborations, reasons, and justifications for their responses than their peers in the cooperative condition. However, results on the follow up reasoning and problem-solving (RP-S) activity indicated that these oral discourse skills did not transfer to the written task, possibly because the children may not have enough time to consolidate their application in another context requiring them to work independently of their peers. Teachers need to be mindful of the apparent delay many students experience in being able to transfer the skills of problem-solving, reasoning, and justifying demonstrated in oral discourse to written text and to provide for more instruction and reflection for these skills to emerge. (Contains 5 tables.)