Second language acquisition studies tries to discover the process of learning a foreign language. In order to do so, a number of approaches were created by researchers. They all try to describe the process of how we acquire second language and what makes language learners successful. Although there are several distinct comments on this topic, researchers agree on the importance of learning strategies. They realized that not only age or aptitudes are the influencing factors of successful learning, but also strategies employed by learners. It has been provided that some strategies can help students to become acquainted with a foreign language. In this sense, we can conclude that the emphasis is put on the (develop)mental process itself instead of the material. In this thesis I am trying to introduce different language learning strategies and find connection between strategy use and learners’ age. To achieve my goal, I would like to have an insight into cognitive approach and cognitive development, since – to my mind – the cognitive stage of learners and their age cannot be separated regarded learning process. Furthermore, I am trying to highlight connections between school performance and strategy use. As we can see later, differences between language learners tend to serve as a base for the examination of this kind. (Introduction)