An electronic learning environment has been developed for introductory physics laboratory work. Extensive use is made of Physlets (Physics Java Applets). The learning environment is tested with fourth semester physics major students at Ghent University. Students prepare their lab work assignment by first reading the lab guide and answering a selection of conceptual questions over the Internet. The tutor reads through the student answers and adjusts the intended instruction. During lab work, students perform experiments, analyse the recorded data, draw conclusions and report their findings. The first results indicate improved student attitudes towards discovery learning, increased engagement with laboratory work for physics and a better understanding of basic physics phenomena, compared to student groups in earlier years.