The present diploma thesis considers the different aspects of proving mathematic or geometric problems in secondary first stage math or geometry class. First, general aspects of proving, with some links to the scientific discipline of mathematics, are examined. Especially in this area, the act of proving is of eminently great interest. After introducing the terms of proving, reasoning and arguing, their meaning in the context of curricula and scholastic standards is examined. Additionally, the fundamental structure of lines of arguments (according to the considerations of Stephen Edelston Toulmin) and the different types of proofs in mathematics is explained. Following this, didactic backgrounds of arguing in the school routine are discussed. Special types of proofs, which are common in geometry class (e.g. similarity proofs or transformational proofs), are covered with descriptive examples. This part also refers to the functions of reasoning in class and finally to didactic difficulties. Subsequently, several possibilities of preliminary practices and trains of thoughts leading to the process of learning how to prove are discussed. Following this, the question of how teachers can generate and advance the pupils need for proofs is considered, together with a discussion about the most suitable level of education to apply these. The particular research work of this thesis finally contains a comparative analysis of a total of five schoolbooks. Three outdated books are deliberately chosen together with two current, modern ones, in order to draw appropriate comparisons between the types of the exercises from approximately ten years ago and those from nowadays. This research work also examines which activities are required from the pupils and what level of mathematical knowledge needs to be present.