Why Do Two Minuses Make a Plus? Exploring How Pre-Service Teachers Explain Negative Numbers

Children often use fingers or objects to support counting with whole numbers, yet negative numbers lack an equally intuitive representation. In this seminar, I discuss a study investigating how pre-service teachers explain calculations involving negative numbers. Using scripting as an approximation of practice, I examine the conceptions teachers draw on through the representations they use and the underlying mathematical structures they foreground. The findings highlight the fragmented nature of explanations of negative numbers and raise questions about how greater coherence in teaching might be supported.