Skinner (1958) expressed the need for an increase in the effectiveness and efficiency of education. In particular, he suggested that programmed instruction could provide such efficiency. The present study used a within-subject design to compare the effects of four types of instructional materials; those requiring overt construction responses, overt discrimination responses, covert reading of text with highlighted key words, and covert reading of standard text. The materials requiring overt responding produced greater learning than did the covert reading materials, with or without highlighting. There was no difference found between the two types of overt responding; nor were there differences between the two types of covert reading materials. Thus, this study supports the assumption that overt responding is more effective. However, the overt response materials also required proportionately more time. Therefore, this showed no benefit of overt responding in terms of efficiency.