This research project examines problem solving processes in moderate to high-ability grade 7 and 8 mathematics students using cognitive load theory as a theoretical basis. This was done using a qualitative method and thematic analysis to identify the theme of cognitive load as it arose during four audio-recorded interview sessions with the six participants. A model is presented that examines the problem solving process based on the data collected in this study. This model proposes that problem solving involves reading, internalisation and classification of a problem. The solver uses mental restructuring and solution strategies to reduce cognitive load. Metacognition is used as a cognitive load monitoring device. Prior knowledge largely determines the chosen solution path and strategies. Unresolved cognitive overload results in confusion which leads to non-solution; cognitive clarity results in a solution. The implications of this model are discussed for teachers and students.