This study describes Singapore students' (N = 607) performance on a recently developed Mathematics Processing Instrument (MPI). The MPI comprised tasks sourced from Australia's NAPLAN and Singapore's PSLE. In addition, the MPI had a corresponding question which encouraged students to describe how they solved the respective tasks. In particular, the investigation considers two tasks the cohort found difficult to solve--a relatively complex task from the Singaporean item bank and a novel task from the Australian tasks.