One of the most central tenets of chemistry education is developing an understanding of the processes that involve the Transformation of Matter. Current German curricula postulate content-related abilities ("Kompetenzen") that are expected to be achieved by secondary students when graduating from the lower secondary level at grade 10. These abilities can further be differentiated as relating to either structural aspects of matter or to aspects of chemical reaction. Little is known of how "Kompetenzen" in these two fields develop over time on the lower secondary level. This study aims at elucidating this development by suggesting a hypothetical learning progression for the lower secondary level. This learning progression is visualised as a Strand Map and is investigated using methods from three statistical approaches: Rasch-analyses, Classical Test Theory, and Bayesian Networks. Concurrent data from all three strands of analyses inform the evaluation of the learning progression and support the notion that an understanding of the Transformation of Matter relies on interrelated "Kompetenzen" to conceptualize Structure of Matter and Chemical Reaction. Moreover, Bayesian networks underline that there is more than one progression when learning about chemistry on the lower secondary level. Contains notes and references.