Following our results and Lim and Pugalee’s (2004) experiences from action research using a rubric for writing in mathematics, we will start in 2015 a research project with a quasi-experimental setting to test for significant effects of using standards-oriented rubrics in formative assessment on student-achievement as a next step. This consequential aspect of validity would add to the quality of the assessment, if it could be statistically demonstrated that working with rubrics can be meaningful and efficient (Baartman et al., 2007).