This mixed-methods study investigated the use of supplementary materials by EFL teachers in Ecuadorian secondary schools. Via the use of teacher interviews (n = 12) it was found that teachers believe the use of supplementary materials increases the motivation of the students, which in-turn improves the learning possibilities of the students. The quantitative sample (n = 695) showed the students' preferences for supplementary materials and confirmed our results that the use of certain supplementary materials does in fact increase the motivation, understanding and participation of the students in their English language classes. Four variables were considered to do this research; motivation of students when any material was used, whether students' participation increased or not when using supplementary material, the third one focused on whether the students felt as though their understanding had increased in class as a result of the use of the material. The final variable aimed to measure whether the student felt their performance in class had improved as a result of the use of the material in question. The results showed that more dynamic and interactive classes are created when teachers use any supplementary material.