The tendency to assess students has increased worldwide (Broadfoot & Black, 2004; Lundahl, Roman, & Riis, 2010). The purpose is usually to assess their knowledge but large scale tests also aim to build foundations to make grading more equivalent on a national level (Lundqvist & Sund, In Press; Sund, In Press). The theoretical tests are suitable for subject matter knowledge but the challenge is to assess practical abilities. This is often done by theoretical tests asking questions on experiences and results from practical work (Cfr the outlines in Ofqual (2015)). Another approach is to develop test with parts containing a practical inquiry. In Sweden the national school agency have developed a national test which include a practical part where the task is related to acidification of lakes. Within this part teachers are expected to conduct a given systematic inquiry to assess student’s achievements supported by well-developed assessment guides. It is well known in earlier research that it is complicated to conduct practical tests (Abrahams & Reiss, 2012; Harlen, 1999). This case study focus on the possible obstacles for teachers when they are assessing practical abilities during a test in a laboratory environment. This type of test and test environment is complicated. The purpose of this study is to investigate the prerequisites for teachers to make an individual assessment of students’ individual abilities during a practical work. Differences in three groups way of choosing equipment in the beginning of their practical test inspired to study the conditions for teachers’ equivalent assessments of student’s independent practical work. The research question is:
What obstacles are present when teachers assess student’s individual achievements?
The results make a number of practical and social obstacles visible. They are discussed in relation equivalent assessment, alternative ways of assessing students’ practical abilities to be able avoid some of the discerned challenges.