How different evaluation formats affected test scores for different tracks of high school biology students was studied in an action research case study. For purposes of the study, "A" tracked students were generally college-bound; "B" tracked students were those who had no desire to attend college, especially those in vocational education, or who were below average students whose advisors thought they would not be able to pass a "college-bound" course. Forty-eight A-tracked students and 45 B-tracked students were the experimental groups. Twenty-nine A-tracked students and 42 B-tracked students served as comparisons. Students in the experimental group took the same test control group students did, but, in addition, they were given an additional three essay questions. Their attitudes about the essay test evaluations were noted. Results suggest that adding essay questions to objective tests supplied by textbook publishers is recommended for A-tracked students, who performed well and liked the essay format. However, B-tracked students found the essays difficult and did not do well. The disadvantages of the essay format outweighed the advantages for the students in the B track. Action research was a good approach to investigating the effects of different evaluation formats for students of different levels of ability. (Contains 26 references.) (SLD)