Making sense of Counting in 10, Jumping in Multiples of 10 and Jumping to the Next Multiple of 10: Challenges in Mental Mathematics for Pre-service Teachers.

The persistent underperformance of South African learners in primary mathematics underscores the limited effectiveness of initial teacher education in equipping pre-service teachers (PSTs) with strong mathematical knowledge for teaching. Recent national initiatives, such as the Mental Starters Assessment Projectand the subsequent Mental Maths Work-Integrated Learning project, have sought to strengthen PSTs’ pedagogical content knowledge by foregrounding mental strategies. Within this trajectory, jump strategies (JS), involving counting in tens, jumping in tens, and jumping to a multiple of 10, have emerged as a critical focus area, yet PSTs’ conceptual grasp of these strategies remains uneven. This study analyses pre- and post-test data from 43 PSTs who completed an eight-lesson intervention on JS, using an embedded explanatory sequential design. Results revealed strong baseline performance with jumping in tens but persistent difficulties with jumping to multiples of 10 and coordinating strategies within start- and change-unknown tasks. These findings highlight the promise and limitations of short-cycle interventions and the need for sustained focus on relational reasoning, language and number lines in preparing PSTs to teach foundational numeracy.