Investigate the development of spatial skills in the dynamic geometry environment of middle school mathematics teachers candidates

In the scope of this study, it is aimed to investigate the effect of dynamic geometry learning environment designed on the basis of Cognitive Load Theory (CLT) on the development of spatial visualization skills of pre- service mathematics teachers. In this way, by apllying to CLT, it is desirable to create an instructional model to develop the spatial skills of pre- service teachers in the Cabri3D learning environment. Individual teaching experiment were used to examine effects of the instruction on pre- service teachers. The teaching experiment was carried out in three steps. These steps were in the form of pre-assessment, teaching sessions and final assessment. Individual teaching experiment has allowed for close observation of participants' spatial visualization and reasoning processes. The study was conducted with four mathematics teacher candidates. In the pre-assessment it is found that generally tasks which have high amount of cognitive load cause increase in the error rates and degree of perceived difficulty of pre-service teachers. It is observed that high cognitive load formed by perceptions, inability to use existing knowledge and experiences in new contexts, lack of conceptual schema, etc. After instruction, it is identified that the content arranged according to the theory, desined Cabri3D materials and teaching sessions realized with respect to defined directions generally decrease error rates of pre- service teachers and percieved difficulty of tasks. According to the level of expertise, pre-service teachers have gained new schemes, and also developed their spatial skills.