The most time consuming part of creating a great WebQuest is finding online resources that match the curriculum and that are readable by your learners. Fortunately there are many pages out there that focus on this problem and many people working to assemble and organize kid-friendly resources. Some of the most useful sites include:
These are great sites to explore while you're still shaping the ideas for your WebQuest. Once you have specific terms to look for, you'll find the custom search engine below to be useful. It searches over 20 educational resource sites simultaneously. Give it a try!