The relative effectiveness of four methods of teaching practical scientific skills to secondary school students

The investigation compares the effectiveness of four methods of teaching students how to perform two practical scientific skills. The methods commonly used combinations of four different modes of communication. Method W uses written instructions only. Method WG has these written instructions supplemented with graphics. Method WGS adds spoken instructions to the combination used in Method WG, and Method WGSD also includes a video-recorded demonstration of the practical task. After teaching random groups (N = 20) of students aged 14-15 years with one of the methods, their effectiveness was assessed in terms of the students' performance on test exercises which required the students to carry out these tasks. The results showed that the methods involving the use of spoken instructions (i.e. WGS and WGSD) were significantly worse than those that did not use spoken instructions. The use of graphics also had no significant beneficial effect, and the demonstration had a significant positive effect only in one task.