Science education research can be categorised into three broad dimensions: knowing science, doing of science and learning about the nature of science. The concerns, doubts and relative importance of each of these aspects in relation to students' learning are debated in the literature. The findings of the empirical research carried out in New Zealand described here are that students do learn and develop science understanding through engaging in practical experiences, which is in contrast with the current view that learning through practical work is inadequate and often less effective than desired. (Contains 1 figure and 3 tables.)