The purpose of my study was to determine the effectiveness of using dynamic geometry software while exploring the properties of quadrilaterals. Dynamic geometry software can be effective if used properly in the exploration process as students construct their own knowledge through constructivism. Students were given the Van Hiele Test as a pretest to determine their Van Hiele level prior to taking a high school geometry course. The results determined that the majority of the students were not at the level needed for the course, which is typically taught at a Van Hiele level 3. Students in the treatment group used GeoGebra while exploring the properties of quadrilaterals using a framework in which students are put at the center of their learning and the teacher acts more like a facilitator rather than being the primary source of information. Students were given a unit assessment after completing the unit and the Van Hiele Test was administered again as a posttest during the last month of the course. The results showed that students in the treatment group performed better as a whole in the unit assessment and had more students advance to the next Van Hiele level, however, it is possible that they may continue to struggle with future assessments that contain a geometry section. The perceptions survey showed that students had a positive experience during this process. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]