A series of four interactive interdisciplinary (but based on science) books, for grades two through five, were created to provide educational materials on tropical rainforests for elementary schools in the Philippines. The books were produced in conjunction with Philippine and American teachers, administrators, and science education consultants. They were then used and assessed for a year in actual classrooms in a variety of six Philippine schools in Mindanao. Comparative tests, before and after using the materials, were given to both teachers and students in participating schools. We observed highly significant measurable learning and improvements in understanding about rainforests. There was much variability in outcomes among the different schools. A highly significant general trend among students, however, was for greater improvement (gain) for students who had lower pretest scores. That trend for individual students extended to the schools, which reduced the discrepancies between public rural mountain schools and schools in urban or city settings, including a private city school.