Web allows learners to investigate any question with a great variety of Web resources, in which they could construct a wider, and deeper knowledge. In such investigative learning process, it is important for them to deepen and widen the question, which involves decomposing the question into the sub-questions to be further investigated. This corresponds to creating a learning scenario that implies the questions and their sequence to be investigated with Web resources. The learning scenario would be useful for the learners to reflect on the constructed knowledge. However, it is quite difficult for them to create their own scenario concurrent with knowledge construction from the contents of the resources. How to scaffold the learning scenario creation is an important issue as Web-based investigative learning aid. Towards this issue, we have modeled Web-based investigative learning process, which induces learners to create the learning scenario by decomposing a question into the sub-questions while searching and navigating the Web resources. In this model, the learning scenario is represented as a tree of questions investigated. This paper also demonstrates an interactive learning scenario builder iLSB we have implemented. iLSB provides scaffolds for the learners to build the tree of questions in learning with Web resources. The results of the case study suggest that iLSB makes learner-created scenarios more structured, and that it allows the learners to promote their reflection on knowledge constructed during investigative learning process. [For full proceedings, see ED571332.]