Online resources can deepen student learning--if teachers design the right tasks and learner supports. In this article, the authors look at instructional websites teachers will want to use with their students. They focus on three types of web-based learning environments--(1) informational reading systems; (2) interactive learning systems; and (3) instructional learning systems--framing their thinking about effective lesson design in terms of two crucial questions: What do you want your students to understand and be able to do? and How can web-based learning environments support your learning goals?