Students who have particular difficulty in mathematics are a growing concern for educators. Graphic organizers have been shown to improve reading comprehension and may be applied to upper level secondary mathematics content. In two systematic replications, one randomly assigned group was taught to solve systems of linear equations through direct instruction and strategy instruction. The other group was taught with the same methods with the addition of a graphic organizer. Students who received instruction with the graphic organizers outperformed those who received instruction without the organizers. They also better understood the related concepts as measured by immediate posttests in both replications. The difference in understanding concepts was maintained on a 2-3 week posttest.