This research was designed to study the effectiveness of using the discrete mental skills in teaching according to Costa's model on brain information processing as well as developing and promoting thinking, creative thinking, and feelings strategies. Two teaching units (energy and chemical reactions) were chosen from the curriculum of first preparatory level. Their contents were analyzed and the concepts were restated per lesson and were taught during the first (energy) and second (chemical reactions) semesters (2013) for two classes (experimental, N= 38 and control, N = 36) of a randomly chosen girls' school, in Benha, Qualubia Governorate. A teacher guide and tests were prepared for logic, decision-making, problem-solving, and critical thinking strategies. Frank Williams' translated test was used for creative thinking and feelings strategies. After completing teaching the contents of the two units, the results indicated relative to the control that there were: 1-Significant increases in the discrete mental skills means and total scores of each strategy, 2-Significant increases in the mean total scores of each strategy, 3-The magnitude of increases in the mean scores of discrete mental skills for each strategy were higher for the chemical reactions unit than their counterparts of the energy unit, 4-The frequency distribution of the student scores according to research variables showed that scores of the chemical reaction unit were mostly grouped at the interval (>70), while those of the energy unit were scattered among the preceded intervals The research recommended the extension of implementing Costa's model in the curricula of all educational levels, and ended with three interrogative suggestions.