Secondary school pupils underachieve in tests in which reasoning abilities are required. Brain-based training of working memory (WM) may improve reasoning abilities. In this study, we use a brain-based training programme based on historical content to enhance reasoning abilities in history courses. In the first experiment, a combined intervention of WM-capacity and reasoning strategies is trained and compared with control group data in "HAVO" (medium track secondary education in the Netherlands). WM-capacity and reasoning strategies of the experimental group improve significantly after three weeks of training. Students achieve significantly better in school tests in which reasoning abilities are tested. The gain in reasoning abilities is also significant 16 weeks after the training programme is completed. In the second experiment, WM-capacity and reasoning strategies are trained independently and compared with control group data in "VWO" (upper track secondary education). Training of WM-capacity did not improve achievements in reasoning tests significantly, but training of reasoning strategies did. However, the results of both experiments cannot be compared because of cognitive group differences between Experiment 1 and 2 (educational tracks). These results demonstrate that brain-based learning strategies to improve reasoning abilities can easily be integrated in history curricula. Furthermore, a six-week training period can improve reasoning abilities of students in secondary education significantly. The study used content-based, non-adaptive training methods that are based on standardised tests. Cognitive WM test scores indicate a ceiling effect which can be explained by the absence of the adaptive element in the training.