The emergence of free, open, online, help forums has transformed tutoring from a private and individual activity into a public and collective endeavor. These forums support asynchronous exchanges between individuals from around the world. Students visit these forums seeking help on specific queries from coursework and receive help from anonymous others. In contrast to help forums designed and supervised by educational researchers, these forums have a grassroots origin. This paper investigates one such calculus help forum for evidence that forum tutors are scaffolding students to contribute to the successful solution of the exercise they posted. An analysis of 200 exchanges on limit and related rates revealed the presence of effective guided problem solving (marked by leading questions and hints), albeit to a limited extent. This work points to the need for discovering ways to augment constructive interactions in popular help forums that have become part of the student learning experience.