This study examined the effect of a hypermedia-enhanced problem-based learning environment in astronomy on sixth-graders' science knowledge, attitude toward learning science, and motivation toward learning. It was found that the students had significantly increased their science knowledge from pretest to post test and also retained much of what they had learned after two weeks. Students' attitudes toward science and their intrinsic goal orientation were significantly higher after using the technology application. Students' science knowledge scores were positively related to their attitudes and intrinsic goal orientation. Such findings suggested that this hypermedia learning environment had a positive impact on the sixth-graders.