The development of general scientific abilities is critical to enable students of science, technology, engineering, and mathematics (STEM) to successfully handle open-ended real-world tasks in future careers. Teaching goals in STEM education include fostering content knowledge and developing general scientific abilities. One such ability, scientific reasoning, is related to cognitive abilities such as critical thinking and reasoning. Scientific reasoning skills can be developed through training and can be transferred. Training in scientific reasoning may also have a long-term impact on student academic achievement. The STEM education community considers that transferable general abilities are at least as important for students to learn as is the STEM content knowledge. We therefore asked whether learning STEM content knowledge does in fact have an impact on the development of scientific reasoning ability. The scientific reasoning ability studied in this paper focuses on domain-general reasoning skills such as the abilities to systematically explore a problem, to formulate and test hypotheses, to manipulate and isolate variables, and to observe and evaluate the consequences.