Dave's ESL Cafe is one of the best Web-based resources for English as a Second Language. The site includes a wide range of activities and interactive environments. Students can write on the Graffiti Wall, learn American idioms, take a wide range of interactive quizzes, and much more. Although this is a commercial site where one can pay to take classes to learn English, there are also several good free areas. This site contains a quick instruction course on proper sentence construction and grammar.
Several quizzes follow the various grammar sections.
Knowledge of frog anatomy is evaluated with the Virtual Frog Builder Game. Students can zoom in on an area to examine it more closely. There is also an interactive Xpedition Hall that provides information on a particular area's language, religion and contemporary status.