Social networks are pivotal for learning. Yet, we still lack a full understanding of the mechanisms connecting networks with learning outcomes. Here, we present the results of a large scale study (946 elementary school children from 45 different classrooms) designed to understand the social strategies used by elementary school children. We mapped the social networks of students using both, a non-anonymous version of a prisoner's dilemma and a survey of nominated friendships, and compared the strategies played by students with their GPAs. We found that higher GPA students invest more strategically in their relationships, cooperating more generously with friends and less generously with non-friends than lower GPA students. Our findings suggest that the higher selectivity of social capital investments by high performing students may be one of the mechanisms helping them reap the learning benefits of their social networks.