Background:
This study examines whether a Role Play Game (RPG) with embedded geological contents and students’ anticipation of an upcoming posttest significantly affect high school students’ achievements of and attitudes toward geology.

Material and methods:
The participants of the study were comprised of 202 high school students, 103 males and 99 females. The students were divided into 4 groups: 1. RPG group with pre-announced posttest, 2. RPG group with unannounced posttest, 3. No RPG group with pre-announced posttest, and 4. No RPG group with unannounced posttest. A 2x2 MANCOVA was conducted on the posttest scores with students’ pretest scores as the covariates.

Results:
The results indicated that: (a) there was no statistically significant interaction effect between RPG and anticipation of posttest on students’ learning outcomes; (b) there was no statistically significant main effect for RPG on students’ learning outcomes; however, (c) whether or not students had anticipated an upcoming posttest significantly affected their geological achievements and attitudes.

Conclusions:
In conclusion, testing has positive effects as a reinforcement to help students both retain their content knowledge and have positive attitudes towards geology.