Assessment of learning plays a central role in the teaching-learning process, and it has been extensively investigated due to the recognized necessity of adjusting didactic models to the new curricula and social demands. The knowledge of assessment is considered one of the components of pedagogical content knowledge (PCK) by some authors and for other authors is considered one component of the knowledge base for teaching. It is also recognized the strong link between knowledge of the educational ends, goals, purposes and values and the knowledge of assessment procedures. In this work, results focused on ten chemistry teachers are presented with the main goal of assessing and describing the knowledge of assessment practices and its close relationship with the purposes and educational aims. The results of the current study are based on semi-structured interviews, schools’ educational projects, questionnaires, evaluations and teacher lesson plans. The data suggest that there exists an inconsistency in the discourse regarding general education and chemistry education. Although the discourse at all levels, including educational projects, planning and interviews, can be considered as innovative, in actual practice we observed a strong tendency toward the teacher-centered approach and summative assessment. The results show that, in general, the investigated chemistry teachers lack the intrinsic knowledge to elaborate questions that assess students´ higher-order thinking, to use assessment results to improve teaching and learning, to inform planning, and ultimately, to perform assessments for learning that regulate and promote the learning process, in line with their own beliefs regarding the objectives of chemical education. As a result, we can infer problems in other PCK components of these teachers.