Mutual learning between teachers and their colleagues plays a vital role in their professional growth. However, previous studies show that collaborative teacher learning tends to be confined to small groups, and that it is difficult to make it explicit, showcase, or transfer teachers' tacit knowledge. This study explores this problem by creating a digital system that allows teachers to create, display, and trade their knowledge products; 508 teachers from one K-12 school created and traded their knowledge products, while 1,148 teachers from other schools participated in the knowledge product transaction on the digital system. Using social network analysis, we discovered that teachers use this method to generate a lot of interaction and that teachers who taught similar subject areas communicated more with one another. There is a significant correlation among each teacher's number of created knowledge products, knowledge products sold, and the number of knowledge products purchased from others. The study has potential to contribute to research on teacher learning, thinking, and actions.