The aim of the present study is to investigate pre-service secondary mathematics teachers' cognitive-metacognitive behaviours during the mathematical problem-solving process considering class level. The study, in which the case study methodology was employed, was carried out with eight pre-service mathematics teachers, enrolled at a university in Erzincan, Turkey. We collected data via think aloud protocols in which metacognitive supports are provided and not provided and with unstructured metacognitive protocols related to the process. The metacognitive support provided to the pre-service teachers and this case caused an increase in the numbers of cognitive-metacognitive behaviours in class level in general. Any pattern was not encountered for the sequences of cognitive-metacognitive behaviours in the process of mathematical modelling during the stages in which metacognitive support was given and was not given but some little patterns were detected. It was noticed that there was no relationship with respect to the metacognitive support and without metacognitive support between and frequencies of cognitive-metacognitive behaviour mathematical modelling progress. The 1st and 2nd grade-pre-service teachers claimed that the metacognitive support contributed to them such factors as understanding and detailing, the 3rd and 4th graders expressed that it enabled them to follow, reach alternative ways of solution. The participants, during the stage in which the metacognitive support was provided, demonstrated more success during the process of mathematical modelling compared with the first stage.