This article presents KnowledgePuzzle, a browsing tool for knowledge construction from the web. It aims to adapt the structure of web content to the learner's information needs regardless of how the web content is originally delivered. Learners are provided with a meta-cognitive space (e.g., a concept mapping tool) that enables them to plan navigation paths and visualize the semantic processing of knowledge in their minds. Once the learner's viewpoint becomes visually represented, it will be transformed to a layer of informative hyperlinks and annotations over previously visited pages. The attached layer causes the web content to be explicitly structured to accommodate the learner's interests by interlinking and annotating chunks of information that make up the learner's knowledge. Finally, a hypertext version of the whole knowledge is generated to enable fast and easy reviewing. A discussion about the affordances of the tool and how it can be used to achieve a scaffolded approach for learning is presented. The evaluation of the tool in a real educational setting revealed its support for navigation planning and knowledge recall as compared to classical navigation techniques. (Contains 4 tables and 7 figures.)