The study aimed at identifying the reasons behind the Jordanian students' drop of performance in the TIMSS 2015 from the point of view of their teachers. Survey method was used because teachers are the most able to decide upon the reasons of this fall and so a questionnaire was designed to recognize their point of view concerning the reasons of this retreat. The study population consisted of 130 teachers of science and mathematics in Ma'an governorate. Teachers whose teaching experience was more than one year to make sure they are familiar with TIMSS tests. Random sampling technique was used to select 90 teachers representing 69% of the study population. For data analysis, means and standards deviations were calculated, and the Schiffe test was used to determine the post differences. The results show that the reasons related to the students themselves and their families got higher averages than those related to the teachers and the curricula. The averages related to the male teachers are also higher than those related to the female teachers. There are no statistical differences in the teachers' appreciation averages of the reasons of this retreat according to their academic specialization (math or science) or their practical experience.