The purpose of this study was to investigate to which extent the criterion-related national assessment aid, ”Hitta språket” for preschool classes, identifies students with weak phonological awareness, in comparison with norm-related screening materials. The study also conducted a survey to examine how preschool teachers conducted their observations, how they interpreted the results and to what extent they considered the assessment aid purposeful. The results of the study show that the low set requirements of ”Hitta språket” in combination with unclear instructions for implementation and results analysis, means that students in need of adjustments and / or special support regarding their reading development are at risk of being missed. The majority of the teachers in the study questioned the assessment aid’s ability to identify students with weak phonological awareness.