The study was a pre-test treatment post-test control design. Three educational districts from the Niger Delta region of Nigeria were treated as clusters. Twenty boys and 20 girls were randomly selected, making up a total of 40 students, in each of Group A, Group B, and Group C. Students in Group A were taught ecology by taking them to the school farm, pond, and nearby stream, while students in Group B were taught ecology strictly in the classroom. Students in Group C were not taught but have knowledge of ecology. Findings of the study revealed a highest performance of Group A relative to Group B and Group C. Students in Group A (field trip) were thus able to perform highest because of their opportunity of having first-hand experience of organisms in their natural habitat. (Contains 1 figure and 6 tables. Appended are: (1) "Lesson plan for field trip method of teaching"; (2) "Lesson plan for expository method of teaching"; (3) "Ecology Achievement Test (EAT)"; and (4) "Grid of questions on the EAT by units and process objectives.")