An activity is an interactive, computer application designed to teach students about a concept through hands-on experimentation. Activities usually present good opportunities for group work as well as individual investigation. Support materials, which include handouts, tables, worksheets, etc., are available for many of these activities and can be accessed from the why page for that activity. A discussion is background material written in the form of a dialogue. Each discussion is devoted to one concept, or more rarely, several closely related concepts.
Some discussions are based on activities, some are independent.
Discussions lead learners to concepts, introduce vocabulary, and help to develop important formulas and structure. A lesson is an overview of how sets of activities and discussions might be used together to introduce a concept. Included are lists of prerequisites and suggested outlines. Links to individual activities and discussions are included. A tool is an activity that can be used with many topics due to its generic nature.