Abstract:

Abstract Spatial skills, including mental rotation, are necessary to understand, comprehend, explore and learn mathematics, but research in mathematics education points out insufficient spatial skills of pre-service mathematics teachers. In this study, the effectiveness of the instruction, designed by taking Cognitive Load Theory (CLT) as the reference frame and executed in the Dynamic Geometry Learning Environment (DGLE), was investigated. The study sample was four pre-service mathematics teachers determined by the purposeful sampling technique. Individual teaching experiment, executed in three steps (pre-evaluation— teaching sessions/instruction— post-evaluation), was used as the method. The collected quantitative and qualitative data were analyzed through content analysis. Findings showed that participants' mental rotation skills were basic or below, before the instruction. They had low mental imagery skills, inadequacies in mathematics language use, and misconceptions about rotation and its components. After the instruction, their mental rotation skills, compassing the mental rotation performance, mental imagery skills, mathematical language use, and concept schemes about rotation and its components, developed. It is recommended that cognitive loads be considered while designing instruction executed in a DGLE.

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