Effectively incorporating technology into the classroom is a great challenge faced by schools today. In this article, we propose a Mobile Computer Supported Collaborative Learning (MCSCL) system to support high school teachers with wirelessly networked Handheld Computers. This system promotes student collaboration and constructivism, without losing face-to-face contact. The MCSCL system was tested during a five week experience in a high school physics class. We observed both its qualitative and quantitative impact. Students and teachers responded very favorably to the system, and the experience also had a strong social impact outside the classroom. The MCSCL system provided a highly motivating learning environment that changed classroom dynamics and promoted collaboration between students. We obtained statistically significant results showing that the environment created by combining the teacher's instruction with the MSCSL system enabled the students to construct new knowledge based upon the previous knowledge provided by the teacher.