One-way covariance analysis (ANCOVA) and a posterior comparison were performed to analyze the differences between the achieve-
ments of the experimental and control groups. The level of significance chosen was 5%. Since no pretest was administered, the grades from
the first midterm examination (at the end of the first six-week school session) were used as the covariate in the analysis. The second
midterm examination (at the end of the PBL experiment in the second six-week school session) was used as the test of achievement. The
geography achievement test contains 30 multiple-choice questions and 20 fill-in-the-blank questions. Each question is worth two points
and the test has a maximum score of 100 points. The English achievement test also has a maximum score of 100 points. The test contains 60
multiple-choice questions and 32 fill-in-the-blank (vocabulary, guided translation) questions, with one point awarded to each correctly
answered question. The test papers were independently prepared and the two teachers involved in this study played no role in the creation
of the test papers.