The fact that teachers can find top-notch lesson plans would be enough to make this site a "must" for the twenty-first century teacher; however, the authors take it a BIG step further by adding opinion questions, new quizzes, word of the day, and more. Students are able to respond to these online elements and instantly see what other students their age around the world think about the subject.
Here is a sample from the student opinion section. One hundred twenty-eight students responded to this question.
This is a sample from their student challenge.