This study investigated whether or not the involvement of some primary school students in practical work, to supplement their being taught by a combination of the lecture method, teacher's demonstrations and class discussions, significantly improved their attitudes to science and their knowledge of machines and water. The sample comprised 180 Jamaican 4th-graders in two urban primary schools. Attitudes to science questionnaires and knowledge of machines and water test (KMWT) were used to collect data. The results showed that there was no statistically significant difference in the students' post-test mean scores on their attitudes to science linked to treatment, but treatment resulted in about 14% and 20% improvement in the experimental and comparison students' attitudes to science, respectively; and, there were no significant gender differences in their KMWT scores. Nevertheless, the post-test KMWT performance of the experimental students was significantly better than that of the comparison students linked to treatment and attitudes to science; and there was a positive, statistically significant but weak relationship between the subjects' (a) treatment, and (b) post-test attitudes to science and their post test KMWT scores.