This study examines science teachers’ assessment and grading practices as well as studentparticipation in the assessment process in the upper secondary school. The teachers wereasked about how and when they assess students and what was crucial when grading students.We asked when they considered students to have developed the following knowledge criteria:aptitude for critical thinking, analytical and practical skills and how they assessed studentsregarding these skills. We report overall evidence-based assessment practices from theteachers’ comments in face-to-face interviews. Teachers’ comments are closely aligned andassociated with long-established beliefs. The assessment and grading practices were found tobe at odds with modern perspectives of assessment as well as its role in learning.