This article traces the development of the wartime Japanese curriculum, which was deliberately designed to implement ‘Japanese’ approaches to science, and its relation to the previously dominant educational approach, learning by doing. It examines the work of Shiono Naomichi (1898–1969), who served as the curriculum and textbook revision director for science and mathematics in the Ministry of Education from 1924 to 1944 and also authored several important textbooks up to the 1950s. While authoring two textbook series in the 1930s and 1940s, respectively, Shiono used learning-by-doing methods to implement ‘Japanese’ ways of thinking within his texts, in response to the demand for the promotion of Japanese spirit. In the succeeding post-war era, Shiono attempted to conceal the relevance of his pre-war and wartime textbooks to the wartime promotion of ‘Japanese’ thought processes and insisted on the educational superiority of his own textbooks over post-war American-style progressive textbooks. By analyzing his shifting claims on wartime education in relation to progressive educational thought, this article portrays the political function of science education and its concealment in post-war Japan. The rediscovery of the political implications of wartime textbooks, as well as a re-examination of their influence in post-war science textbooks, will enable us to critically scrutinize the political features of contemporary Japanese science education.