Summary.The comparison of data from two vocabulary‐learning studies involving a total of 2,483 males and females in the fifth and sixth grades suggests that ‘common sense’ decisions regarding the selection and assignment of learning materials may be inefficient if not detrimental. There is evidence to postulate that low ability pupils are the primary recipients or victims of the less effective materials. The data suggest that oversimplified learning materials may yield negative transfer and thus actually deter lea