3D Virtual Environments (VEs) are a technology which has a significant impact to students' learning. However, the factors that shape the educational experience when using them are not adequately studied. The present study attempts fill this gap. It reports the development and validation of a scale to measure the factors hypothesized to have an impact on ones learning experience when using VEs in informal learning settings. For that matter, a VE was developed presenting the work of NausicaPastra (an artist/sculptor). The target group was adults and a total of 541 individuals participated in the study. The following factors were considered: perceived learning efficacy of the application, perceived ease of use, presence, motivation, perceived application's realism, interaction, as well as the enjoyment when using a VE. These factors were measured through a questionnaire. The exploratory and confirmatory factor analysis confirmed that the scale is able to measure 6 out of 7 of the above factors (interaction was not included) through the 24 questions that were retained in the final version of it, with a considerable reliability and validity. The factor structure of the scale is also discussed.