Practical (laboratory) work in science education has traditionally been used to allow students to rediscover already known concepts and ideas, to demonstrate concepts taught in the classroom or, in the case of inquirybased science curricula, to teach concepts. Often, these laboratory practicals do not achieve their goals and may even confuse or demotivate students. It is not that using 'wet' practicals is intrinsically wrong; rather, it isthat they are often used for the wrong reasons. They do have a place in science curricula --for the conveyance of tacit knowledge that can only be achieved in the laboratory setting. In our view, their use should be restricted to that.
Non-laboratory practicals (`dry labs'), and especially multimedia practicals, tend to be used for completely different reasons. They are best used to help students achieve specific cognitive skills (such as analysis, synthesis and evaluation) needed to practice science and to carry out scientific inquiry. This article sketches the problems associated with the use of dry laboratories in science education, presents design considerations for the use of such practicals in science education and presents examples of innovative non-traditional practicals.2
Traditional Wet laboratoriesLaboratory work is an accepted part of science instruction. Given its important place in the education of youth, it is surprising that we know so little about its functioning and effects (Gallagher, 1987: 351) Although most scientists and science teachers look back on their experience of university practicals positively, and feel that the `average' practical they followed was of reasonable quality and was worthwhile, there are some major concerns. A review of the literature (Kirschner & Meester, 1988) dealing primarily with undergraduate science education yields the following criticisms from students and teaching staff.Practical work provides a poor `return of knowledge' considering the amount of time and effort invested by staff and students.• All too often, work done in a laboratory simply verifies something already known to the student.• Too much time is wasted having students perform trivial experiments.• Usually, the practicals cannot fail. Years of effort have produced foolproof `experiments', where the right answer is certain to emerge for everyone in the class if the laboratory instructions are followed.• It is not at all uncommon to find that students have no understanding of the processes and techniques which they have previously used in the laboratory.• Non-trivial experiments tend to overwhelm students. Either they require the student to solve problems beyond their comprehension or they allow insufficient time for satisfactory completion.• Students almost never have the chance to spend time watching an expert conduct an experiment.• The supervision of laboratory work is often inadequate, in that assessed work is often not marked and returned soon enough to have an effect on learning. Assessment (and penalising) is often arbitrary and has little teach...