The purpose of the present study was to compare the effects of two different teaching methods on students' comprehension in Mathematics: pictures with concurrent narration versus pictures with on-screen text, during teaching triangles, a lesson in Mathematics. Forty primary school children (boys and girls) selected to participate in this study. Students split into two experimental groups with the technique of simple random sampling. The first group consisted of students who viewed and listened (pictures with narration group), while the second group consisted of students who viewed (pictures with on-screen text) a presentation of triangles. A recall test was used to evaluate students' comprehension. The results showed that students' comprehension was better when triangles' presentation (pictures) was accompanied with spoken words, than with printed words. The pictures with narration group performed better than the pictures with on-screen text group, in recall test (M = 4.97, SD = 1.32) p<0.01. Results are consistent with the modality principle in which learners are more likely to build connections between corresponding words and pictures when words are presented in a spoken form (narration) simultaneously with pictures.