This dissertation reports on the secondary analysis of data obtained in 2013 about first-year university student’s conceptual understanding of concepts related to simple DC-circuits. The aim was to investigate the nature of conceptual understanding of students entering first-year physics at a South African university, and to explore how their conceptual understanding relates to contextual factors. Data collected from 815 participants comprise contextual data about each participant and responses in the DIRECT-instrument (Determining and Interpreting Resistive Electric Circuits Concepts Test). The conceptual framework for this study was based on a combination of the model about the effectiveness of science teaching and the critical outcomes related to electricity and electric circuits, which involve aspects of current, energy, potential difference and the physical aspects of circuits. The contextual data included information at personal, classroom and school level. Data were analysed using Rasch analysis. The study found that students entering a first-year physics module at a South African university have poor conceptual understanding about simple DC-electric circuits. The analysis of the DIRECT-instrument revealed that students had difficulties understanding concepts relating to parallel circuits, confusing terms such as voltage and current, and current and energy. They also struggled to relate a circuit diagram to an actual circuit and issues regarding short circuits were prominent. The analysis of the contextual data revealed that students’ degree of exposure to practical work does not imply conceptual understanding of DC-electric circuits. Factors that relate with conceptual understanding included students’ attitudes towards science, gender and previous achievement in Science, Mathematics, and English. Key terms: Conceptual understanding, DC-electric circuit, Misconception, Aptitudes / Dissertation (MSc)--University of Pretoria, 2021. / Science, Mathematics and Technology Education / MEd / Unrestricted