Progress monitoring of academic achievement is an essential element to prevent learning disorders. A prominent approach is curriculum-based measurement (CBM). Various studies have documented positive effects of CBM on students' achievement. Nevertheless, the use of CBM is associated with additional work for teachers. The use of tablets may be of help here. Yet, although many advantages of computer- or tablet-based assessments are being discussed in the literature (e. g. innovative item formats, adaptive testing, automated scoring and feedback), there are still concerns regarding the comparability of different assessment modes (paper-pencil vs. tablet). In the study presented, we analyze the CBM data of 98 fourth graders. They processed the exact same computation items once with paper and pen and once in a tablet application. The analyses point to comparable results in the test modes, although some significant deviations can be found at item level. In addition, the children report perceived benefits when working with the tablet.