"Informal Forum," grounded in constructivism has been developed to foster active learning and deep understanding. Learning is an interdependent process, and is most effective when students construct their own meaning of knowledge. If one believes in the value of constructivist learning, it is important to teach how we preach in higher education. This activity consists of three phases of learning procedure, including "preparing" students for the forum, "staging" the classroom forum, and "reflecting" on the forum activity. The tasks in each phase will be explained and examples will be provided. In this activity, students demonstrate high levels of cognitive thinking in which peer teaching is evident and deeply embedded through dialogue among participants. Informal Forum successfully helps students learn about child development theories and other contents in a teacher preparation program. The results of students' learning were revealed through their reflections right after the forum.