We defined learning while searching and browsing on the Web as "learning by searching." We used concept map to evaluate how users' knowledge structure changed as a result of their learning by searching. The influence of different topics and different scenarios was also investigated. In the experiment, participants were divided into divergent and convergent scenario groups. They were asked to assume the role of a journal editor and search for information to be presented at an editorial meeting. They performed two tasks within the topics of environment and travel. We compared the two concept maps drawn by the participants before and after the search and analysed the web pages browsed by the participants during the tasks. The results showed that the participants' knowledge representation dynamically changed through learning as a result of searching, and the topics and scenarios influenced their processes and changed their conceptual structures before and after searching.