Figure 2. This graph displays the difference in academic achievement (pre-test score-post-test score) for the treatment (n=27) and control group (n=13)

From

Effects of Animals in Post-Secondary Science Classrooms on Academic Achievement, Academic Retention, and Intrinsic Motivation

Casey Krull, Josie Suchomel, Michael Bechtel

American Journal of Educational Research. 2015, 3(9), 1193-1207 doi:10.12691/education-3-9-21