In this project aims to calculate the proportional difference in the development of skills among students using the Computer Assisted Teaching (CAT) and those without. To this end, we propose the hypothesis that the proportional difference in the development of skills among students using the CAT and those without, to study the subject Operating Systems is 30%. This will define the basic research project as a Quasi-Experimental design and correlational form, where they took 2 samples of 89 students, forming groups: CATG, which used computer-assisted instruction, and not used, NCATG. These groups was administered as a questionnaire and obtained partial notes on the subject. To obtain the results, we evaluate the hypothesis and compared the groups formed in the development of skills and academic performance.