This is potentially the first study that addressed the Puerto Rican high school students' chemistry knowledge acquisition using traditional teaching and Physics Education Technology. The problem addressed by this quantitative comparative quasi-experimental study was that students' showed a disadvantage on chemistry knowledge acquisition over other science courses as indicated by Department of Education in Puerto Rico META test results, which showed a decrease of 2.9% in high school students' chemistry knowledge acquisition when compared to the previous year test results. The purpose of this study was to determine whether a difference existed in knowledge acquisition of a chemistry topic taught using Physics Education Technology (PhET) computer simulation and traditional teaching lecture technique among high school students from two private and two public schools in Puerto Rico. This study followed constructivism theory. A total of 117 high school students participated and completed the molecular geometry pre and posttests in this study. Three research questions addressing any differences between PhET and lecture teaching for the molecular geometry topic were performed. Data results were statistically analyzed using ANOVA tests through SPSS. There were no statistical differences between traditional lecture teaching and the use of PhET computer simulations, neither for private nor for public schools, or between them. However, the mean gain increased in all private and public participating schools when PhET computer simulation were used for the molecular geometry topic, therefore, indicating PhET computer simulations can be used to enhance knowledge acquisition in Puerto Rican chemistry high school students. Future recommendations include increasing sample size, expanding the study to additional educational regions, use of other chemistry topics, expanding to college level and using tests in Spanish. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]