This study models a virtual experiment environment (VEE) by adopting the Petri net theory. Petri net-based VEE can record the experimental activity processes of students and evaluate the students' learning abilities. Petri nets can be used as visual-communication aids, and are similar to flow charts, block diagrams, and networks. Consequently, the experimental steps can be easily transferred to the Petri net model. Analysis of the collected data with the Petri net model indicates that errors made by students during experiments can be categorized into two major types, namely, measuring and procedural errors. This work implements a Petri net-based VEE for physics experiments. A total of 72 third-year junior high school students participated in this research. Both pretesting and posttesting are performed to ensure that the Petri net-enhanced VEE is useful.