Abstract
Research carried out amongst adolescent students with learning difficulties is consequential to
the delay/deficit interpretation of performance: Is performance immature and development
simply delayed or does a processing deficit underlie performance difficulties so that
development is impeded? This study investigated what strategies three students in Year 10
applied to simple addition problems. Performance was analysed on a trial-by-trial basis and
strategy variability within problems was examined. After participating in ten years of formal
schooling, these students still did not know the basic addition facts (including tie facts, and
facts to problems with an addend of two and ten). Their performance based on strategy use was
not consistent with a processing deficit interpretation but neither could it be considered simply
delayed. Understanding the extent of the difficulty experienced by some students in acquiring
basic number facts is imperative to developing appropriate interventions.