Research on the relationship between learner aptitudes and presentation modes has taken several approaches - and raised a number of questions. This study sought to clarify the relationships between modes of presentation (verbal vs. spatial), explicitness of presentation (little or much), and student aptitudes (verbal vs. spatial). Explicit guidance clearly was helpful in teaching the fourth-grade subjects, regardless of type of aptitude, how to compute surface areas of two- and three-dimensional objects. The relationship between mode of presentation and aptitude was less clear. The authors discuss their findings at length and suggest several areas for future aptitude-treatment-interaction research.