Background: Within the Kingdom of Saudi Arabia there is the belief that its education system is structured to prepare its students to meet the demanding requirements of the 21st century. However, the country has been recording low average scale scores in the recent Trends in International Mathematics and Science Study (TIMSS) assessments. Even with the progress that the Ministry of Education has made in Saudi Arabia over the years, international mathematics assessment scores have been a regular disappointment. For example, the recent TIMSS scores published in 2015 categories Saudi Arabia among the five countries with lower average achievement in Mathematics around the world. These results also reveal that Saudi Arabia has an average scale score of 383 while the international average is 500. This study is an attempt to suggest causative factors giving rise to this poor performance. Method: The study followed a quantitative approach employing data acquisition questionnaires in a relatively large sample of teachers (n=326). The instrument used for data collection in the study was a survey constructed using a redesigned TIMSS survey for 2015 and following a pilot study. The survey collected information such as the academic and professional background of the teachers: instructional practices; classroom resources; and attitudes towards teaching. The variables were compared using correlation in mathematics teachers of 4th-grade student. The resultant correlations were used to inform the construction of the relevant model for Structural Equation Modelling using Smartpls™. The study sample consisted of the 326 Mathematics teachers for fourth grade. Results: The findings show that student achievement is affected by a complex set of causative factors such as: teacher confidence, teacher satisfaction, teaching methods and classroom experience. The findings were reliable on the whole, as most of the path coefficients had a p-value less than .05(i.e., statistically significant), and with respect to the goodness of fit of the model, there was a large fit. Conclusions: Strong relationships between the complex set of causative factors call for additional development of assessment practices in mathematics education in KSA. In this study, the associations were confirmed via Smartpls™ and outcomes discovered that there was a significant and positive relationship among some variables such as teacher interaction, confidence, satisfaction, teacher emphasis on academic success, leadership support and classroom experience. Therefore, in order to improve TIMSS scores, progress and development in leadership, assessment and strategies in supporting teachers are recommended.