Educational evaluation and standardised testing are widely discussed issues since at least the first PISA study. Typical topics include the research and comparison of effectiveness of educational systems, individual and group based predictors of achievement, development of academic performance over time but also the question of educational equality on the individual, class or societal level. While the influence of social origin variables as socio-economic status (SES) and minority status (in Europe mostly immigrant background) is well documented, the strength of those influences differs strongly with regard to countries, educational systems and grade level.

 Up to this day, educational policy in Switzerland is federally organised and within the responsibility of each canton. However, in the last years efforts have been made to standardise mandatory schooling with respect to length of schooling and curriculum. The new curriculum “Lehrplan 21” represents a milestone in the history of the Swiss educational system, focussing on competencies students should attain rather than curriculum contents. Standardised testing tools, providing feedback to facilitate students learning processes and providing teachers with a curriculum oriented objective measurement for students achievement as "Stellwerk" and "Klassencockpit" are becoming more important, and so does the need of developing those tests further with regard to the new curriculum. For that reason, the cantons of Zurich and St.Gallen are currently developing a new learning and testing tool called "LernLupe", which aims at students from grade level 3 to 6 in primary schools, allowing to assess their competence development in German and mathematics over four years. Results from LernLupe are supposed to help students and teachers to improve and individualize students’ learning strategies, but also to give teachers feedback which allows them to adapt their teaching and instruction methods to the requirements of their classes.

 The influence of SES on academic achievement is well researched and undisputed (e.g. Sirin 2005). As studies show, Switzerland is a country where the connection between social origin and academic performance is rather strong (e.g. OECD 2013). With respect to development over time, studies show, that the achievement gap in reading skills as well as mathematical skills between students from a more favourable and those with a less favourable social origin tends to widen over time in primary education (for an overview, see Neumann et al. 2014), although some research indicates, that at least in mathematics the achievement gap is rather stable over the first years of schooling, between the age of 7 and 11, and tends to widen between the age of 11 and 15 (Leibhan & Takongmo 2015, Caro et al. 2009).

This paper addresses the following research questions:

-       How do reading and arithmetic skills as measured by "LernLupe" improve between grade levels 3 and 6 in the respective cantons of Switzerland?

-       How much are those skills influenced by social origin in terms SES and immigrant background?

-       Does the influence (the gradient) of social origin change over time between grade level 3 and grade level 6?

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