Although this study might suggest that method B causes higher scores than method A, this cannot be absolutely determined. This is because there are many factors that are involved in this experiment and are not accounted for. For example, we do not know if one class was already getting better results before the implementation of this method. If that was the case, it would suggest that the results could be attributed to the differences between the teachers, or the differences between the students. The general problem that precludes a cause-and-effect explanation is that we do not have a way of determining which factor is the one that made the difference with the students.