A Web_Soc tutoring system for recursion concept learning is proposed. The system integrates different modes of learning, synchronous and asynchronous, collaborative and individualized, into a World Wide Web (WWW) environment. The paper proposes a collaborative learning protocol. Based on the protocol, the principles of the Socratic dialogue are applied to the collaborative learning of recursion concepts. In order to evaluate the effects on learning of the Web_Soc system, an educational experiment was conducted. The results show that the effects from the Web_Soc system were more obvious than merely studying articles.