This paper gives an overview on Portuguese political and educational systems. After, it attempts to provide an understanding on how textbooks were chosen in previous decades. So, it addresses the Portuguese textbook approval systems, in particular the model that emerged in 1947 (unique textbook) and the contemporary published opinion about it. Regarding mathematics, the first unique textbook was approved in 1950; it was the Algebra textbook for the 3rd cycle of Liceus (upper secondary school). This paper discusses the criticism on the Algebra textbook that was published in the journal Mathematics Gazette. In our study we analysed two versions of the first unique Algebra textbook in order to trace changes in content, in this paper we will present part of that analysis. The paper is based mainly on legislation, newspapers, educational magazines and mathematics textbooks.