The Industrial Association of Porto was founded in 1849. Industrial education was one of its first priorities, having created the Industrial School of Porto in 1852. In 1853, António Luís Soares, a professor of this school, published several arithmetic lessons for primary education in the Newspaper of the association – Lecture of the arithmetic elements in the Association’s primary school class. These lessons were addressed to teachers who should reproduce them to their students. The author includes several considerations about the importance of propagating basic math instruction, either for industry or for the trade workers, two important activities for the city. In this paper, we will present these classes and show how this text may be used in the classroom (primary source in the history of mathematics).