The objective of this study is to apply Game Theory as a motivating element in the teaching of mathematics in those classes in the 3rd series of secondary education in the state schools of the city of Rio de Janeiro which have already frequently presented difficulties in learning this discipline. We construct a didactic sequence to be applied in the classroom: presentation of a brief history of the theory; the realisation of the game, the Prisoner s Dilema; and a subsequent explanation of the results predicted by Game Theory for this game, introducing the concepts of the result matrix and the dominant strategy. We then apply a simple self-assessment test in order to consolidate these topics. Once the students are familiarised with the basic concepts of Game Theory, we realise the Ultimatum Game in the classroom in order to compare the results with those obtained by Bianchi, Carter e Irons and Castro e Ribeiro.