Group work can engage students in active learning, yet students often resist working with peers in class. We investigated the impact of five minimally structured, easily implemented group work strategies used during weekly problem-based discussion sections in two introductory chemistry courses through student surveys and quiz score analyses. Students reported increased interaction with their classmates as a result of group work but did not feel more prepared for the weekly quiz. Interestingly, students' performance on the weekly quizzes was anticorrelated with the strategy they felt prepared them best for the quiz. Students at the introductory level appeared unable to "self-assess" what helps them learn. However, group work strategies with greater interaction between students were associated with higher quiz scores. Furthermore, we found that implementing specific strategies over time resulted in more collaboration than simply instructing students to work together. These results are consistent with previous work that highlights the importance of student interaction in learning and suggest that positive interdependence can be created among students even in a less structured collaborative environment.