The present study deals with initial formation of concept of decimal system in second year of education at primary school in Mexico (City of Puebla). Our research is based on Activity Theory conception of teaching-learning process and of gradual introduction of scientific concepts in school age. The method has been designed and worked out with the help of actions in which logic. symbo... https://www.parisnaturalfoodes.shop/product-category/complete-cookie-apple-pie/