The present study aimed to test the effect of the problem-posing instruction experimentally based on the extended active learning framework on the development of Turkish middle school sixth-grade students' (N = 19) problem-posing and -solving skills with whole-number operations. The training programme was completed in 13 lessons over a seven-week period. The posed problems were analysed based on their mathematical validity and semantic complexity, and their solutions were analysed using a four-phase rubric. The students significantly improved their problem-posing and -solving skills. Furthermore, students improved their skill to pose more complex problems in terms of number and type of semantic structures after the training programme.