Thinkquest is a free online platform for teachers and students sponsored by the Oracle Education Foundation. It includes an online project environment for students to collaborate, and a library of content and projects created by other students. The document then provides step-by-step instructions for teachers and students to access and use Thinkquest, such as how to log in, view other student projects, start your own project by registering, and create and save pages for a new project using different formats like text or lists.