Learning progressions (LPs) are descriptions of students' growing sophistication in the understanding of a particular construct through a curricular sequence. They are particularly useful for organizing complex constructs for which students do not necessarily connect concepts as taught in different courses. However, they are challenging to construct, because they attempt to linearize students' inherently nonlinear learning. As a result, it is essential to have methods to assess students' arrival at particular steps along the progression. One tool readily available to instructors is concept inventories (CIs). We have mapped published CIs to LPs for acid-base chemistry. The alignment not only provides an assessment that professors can use to pinpoint student learning, but also creates another tool to verify hypothetical LPs. We have compared the types of questions asked on CIs in chemistry, biology, and biochemistry, as well as in some standardized test banks. The mapping of questions from CIs to steps on the LPs allows refinement of the LPs and reveals gaps in assessment tools for sophisticated concepts. This alignment is a novel addition to the cycle of validation of an LP.