A conventional classroom is filled with diverse students from various backgrounds, and academic abilities.The benefit of differentiated instruction is lost when all students are assessed using standardized tests based on the "one size fits all" philosophy. In this research we will discuss the impacts of implementing differentiation in assessment on primary students' performance. Additionally, the reasons teachers overlook differentiating assessment despite the development of assessment strategies and the quality of teaching. As Bahrain's future teachers who will begin their teaching endeavor in less than a year, it is within our responsibility to break the cycle of "One size fits all" when it comes to assessing students.Expecting identical achievements from every student without considering their differences has a negative psychological impact on students such as losing confidence, dropping out of school, and neglecting educational pursuits (Noman and Kaur, 2014).In such diverse classrooms, differentiated instruction is commonly employed as an approach or a practice to meet the diverse requirements of students.However, when it comes to assessment, teachers continue to rely on traditional assessment procedures for all students in the classroom, regardless of their individual learning abilities.Especially so, given that differentiated assessments can assist teachers align their teaching strategies with students' educational needs (Tomlinson, C. A., & Moon, 2014).Therefore, this research aims to answer the following question: how can we implement differentiation in assessment in Bahraini primary classrooms?