Team invasion games (TIG) make up a large part of the PE curriculum in Scottish schools. It is important, therefore, to understand the environmental conditions that contribute to pupils' motivation to learn to play TIG. Consequently, this study aimed to identify the teaching behaviours exhibited when teaching TIG using a game-based approach and a skill-focused approach to teach secondary 1 (S1) basketball. Additionally, this study investigated pupils' and teachers' thoughts about their experiences during each basketball lesson. We found a change to more mastery behaviours during the game-based lessons and very similar percentages of mastery and ego behaviours during the skill-focused lessons. The game-based teacher discussed the pupils' performance in terms of game performance and understanding, and the skills-focused teacher discussed the pupils' ability to execute game skills. The pupils in the game-based class discussed game understanding, teamwork, enjoyment and involvement. The skill-focused class valued skill learning and evaluated their performance based on the successful execution of game skills. The findings from this study suggest that game-focused teaching strategies appear to promote a mastery oriented motivational climate and, therefore, have the potential to increase pupils' motivation in PE and TIG. (Contains 5 tables.)