To attempt to appreciate how the relationship between children and computers affects learning, and how educators can guide enthusiasm for virtual environments towards gaining understanding of scientific processes, this study evaluates three educational websites in the subject area of Plant Biology at Key Stage 3, and identifies the characteristics of an effective web site for teaching the subject. Also, it aims for the content to be considered in a wider context, concluding that the important factors in success of the sites, and the activities they provide, are readability, ease and speed of access, manipulation and navigation, clear instructions for each activity, plus relevant coherent content. Increases in pupil skill levels, enabling participation in a Virtual Experiment, are apparent during the research. Exploration of Web Evaluation Criteria is critical if we are to improve our children's educational experiences using this medium, and the analysis may prove to be useful foreducation professionals who strive to select and use, or indeed develop, enriching internet-based instructional materials to consolidate or extend prior pupil learning.