The difficulties of learning chemistry are related to the nature of chemistry itself and the methods by which chemistry is customarily taught. Frequently, the way of presenting chemistry does not take into account the psychology of the learner. With senior school pupils (over 1600 were involved) in the Emirates, a series of studies was conducted, all based on ideas from information processing. The study involved various diagnostic surveys of areas of difficulties, followed by the re-design of several large portions of the curriculum presentation in line with the approaches research indicates would generate better understanding and more positive attitudes. These materials were then used to see if better understanding and more positive attitudes were observed. This paper focuses on the outcomes in terms of understanding. The new teaching materials were designed explicitly in such a way that the working memory demand was lowered. To develop more positive attitudes, applications were stressed. The curriculum content was not changed, teachers were not trained in any way in the use of the materials, and the time allocation remained the same. Pupil performance in four major areas of the curriculum was found to improve, on average, by 13%. The results confirm previous studies which showed the critical importance of teaching within the working memory capacity of the learner. (Contains 1 table and 4 figures.)