The aim of this study is to research perceptions of primary school teachers in England about the implementation of the national levels of students' attainment and Standard Assessment Task (SAT). Teachers' views and opinions were studied by using a semi-structured interview created for this purpose. The following themes are explored: procedure of determining the students' level of attainment, responsibility for achieving high level of attainment, providing assistance to teachers in achieving the defined levels as well as what happens if students are under achieving and who and how provide help to teachers if they have problems to reach the required standards. The research involved twelve teachers from Hertfordshire. The respondents stated that the assessment of teachers should not be neglected in the process of student assessment since only the achievements of students in SAT are favoured. In addition, it is highlighted that personal and family context should be taken into account when assessing student achievement and based on that assessment the performance of teachers and schools should be estimated. Although teachers consider themselves to be largely responsible for achieving the results, they also point out the significant role of students, as well as the entire school and family environment. In this context, participation of school management, educational psychologist and teaching assistant are highlighted in the process of improving student achievement. Although the size of the sample does not allow the generalization of the outcomes, the research results indicate the tendency which can be significant for the process of standardization of education in Serbia.