Classrooms are complex in their real sets. To understand such sets and their emergent patterns, network approach provides useful theoretical and methodological tools. In this work, we used network approach to explore two domains of complexity in a classroom: the interpersonal domain, via social networks; and the representational domain, through collective semantic networks. This work is grounded in both Social Network Analyses and Social Representation Theory for gathering information from interpersonal and representational domains. We investigated a physics high school classroom by proceeding sociometric tests and by using words freely evoked by students to explore relations between students' dyad's weights, in social networks, and emerging consensus in semantic networks. Our findings showed closer relations between social ties' weight and consensus formed on intra-school representational objects, while consensus on extra-school representational objects is less dependent on the classroom interpersonal ties' strength.