What's a WebQuest?
It is research done by the students through the Internet. It is a longer research than the one done in Treasure Hunts.
They are given a task that has to be done through a guided process. At the end, the student has to hand in a sort of essay or project. The great difference in WebQuest is that the assessment has to be carefully planned.
It was first developed by Bernie Dodge.
In Spain, the two main people who have developed WebQuests are Isabel Pérez, especially English Webquests, and Sebastià Capella, who focuses on Maths and Science.
Definition in Wikipedia
Five rules for writing a great WebQuest by Bernie Dodge
Isabel Pérez Webquest in English