Introductory programming seems far from being successful at both university and high school levels. Research data already published offer significant knowledge regarding university students' deficiencies in computer programming and the alternative representations they built about abstract programming constructs. However, secondary education students' learning and development in computer programming has not been extensively studied. This paper reports on the use of the SOLO taxonomy to explore secondary education students' representations of the concept of programming variable and the assignment statement. Data was collected in the form of students' written responses to programming tasks related to short code programs. The responses were mapped to the different levels of the SOLO taxonomy. The results showed that approximately more than one half of the students in the sample tended to manifest prestructural, unistructural and multistructural responses to the research tasks. In addition, the findings provide evidence that students' thinking and application patterns are prevalently based on mathematical-like mental models about the concepts of programming variable and the assignment statement. The paper concludes with suggestions for instructional design and practice to help students' building coherent and viable mental models of the programming variable and the assignment statement.