In Africa, and particularly in Benin, nutritional diseases are frequent, and even account for 45% of deaths among children aged 0 to 5. This problem, combined with the low level of human nutrition among schoolchildren, means that learning about nutrition is fraught with difficulties. In order to provide a solution to this problem, this book presents the major physiological phenomena involved in the supply of nutrients to the human internal environment, namely digestion and intestinal absorption. A problem-based analysis of the data collected through observation of classroom sessions shows that the difficulties of learning about the supply of nutrients to the human internal environment are many and varied, and can be classified into the following broad categories: epistemological difficulties linked to mathematics, chemistry and the specific vocabulary of nutrition; sociological difficulties linked to the poor level of understanding of some students; and analytical and methodological difficulties. In the face of these difficulties, solutions have been proposed in this book to overcome them.