Students in grades four through twelve from fourteen schools learned to build their own immersive virtual environments (VEs). This required them to decide on the theme of their VE, to determine what objects to place in it and what behaviors these objects would exhibit, to model their objects using CAD software, to specify the form and function of the VE for professional programmers to use as they assembled the VE, and to perform assigned tasks when they visited the VE. Although the level and nature of student activity varied from school to school, the students were generally very successful. The VEs they constructed revealed a great deal about how they constructed an understanding of the content their VE represented. Data from a questionnaire showed that they enjoyed building and visiting their VE, and that their enjoyment, ability to work in the VE, success, and their sense of presence were all interrelated. Data from a small subset of students showed that building a VE improved low-ability students' (but not high-ability students') understanding of the VE's content. These findings were interpreted within a framework built from constructivist theories of learning and understanding.