This site started as a class activity.
In my courses when discussing different concepts I would say to the students, "ok, now give me a concrete example". The examples were personally relevant, from the news, media, pop culture, or anyplace that sparked their creativity and imagination.
As my teaching evolved so did my use of concrete examples. Soon I was using CNN.com or GoogleNews.com to find examples in class and discuss the concepts from the lecture. From there I experimented with in-class activities where they would self-generate examples or find examples themselves online. In some classes I would have the students write short papers about real-world examples of the material. Eventually I developed a host of in-class activities, out-of-class activities, extra-credit assignments, and papers devote to using their knowledge. (see list of ways to use ConcreteExamples)
The purpose of each activity was based on research-proven techniques of learning by example, and it drew heavily from the IRAC concept I learned during law school (learn more). More importantly, the students were learning critical thinking skills they could transfer to other courses and their own lives even after the class was over. And they enjoyed doing it! They found it fun and rewarding to actually use what they were learning.
And then I realized posting online would be a way for student learning even after the class was over, as a type of central hub that is both updateable and available to everyone, not just the students. With Ravi Iyer, the co-creator of the site, we are hopeful that using ConcreteExamples is a way for everyone to gain a better understanding of the world around them.