This paper describes the design and evaluation of COLER, a computer mediated learning environment that includes a software coach to help students collaborate while solving Entity Relationship modeling problems. Unlike previous work generally emphasizing dialogue analysis or expert models, this work evaluates a new approach to supporting collaboration that identifies learning opportunities based on differences between problem solutions and tracking levels of participation. Results of an evaluation process explained below show that good quality advice can be obtained through these knowledge sources, although other knowledge sources may fill in gaps relative to the expert's performance. This work demonstrates how intelligent agents can produce reasonable collaboration advice in domains for which structured problem solutions exist by using a few basic knowledge sources. We discuss how COLER?s design supports collaboration and implications for the design of future constructivist learning environments.