This study compared the effects of computer and print text density on learning using 48 undergraduate teacher education majors as subjects. Three separate studies tested the effects of text density and presentation modes (print or computer), learner control, and screen density. Dependent variables for the first two studies--which were related--were differing types of learner achievement (knowledge, calculation, and transfer), lesson completion time, and learning efficiency. The study on screen density measured student preference. The data showed that low-density text was read faster and perceived as more sufficient than the same text presented in a print format. It was also found that when text density was used as a decision variable, learner control groups learned better than groups receiving standard materials. The results indicated that the less skilled readers typically selected high-density text while the skilled reader selected low-density text. Thus, it is suggested that text density could be used as an adaptive strategy with appropriate changes in text density throughout the lesson. The text is supplemented by three figures. (42 references) (EW)