Riddle is a new service for creating polls, quizzes, and what they call commenticles. The polls and quizzes that you create in Riddle can be image-based or simply text-based. If you choose to use images to represent answer choices you can have text appear below the image. Commenticles are polls that are based upon an article that you share. The purpose of a commenticle is to survey an audience for feedback about an article that you have shared with them. All polls, quizzes, and commenticles created in Riddle can be shared by embedding them into a blog post as I've done below or by sharing the poll's link on Twitter (I did that earlier today), Facebook, or any other social network.
Applications for Education
Riddle's format of using images as response choices could make it a good option for giving informal quizzes on topics that require a lot of visuals. For example, a quiz on fractions might use pictures which represent various fractions. A quiz on art history might use Riddle to showcase works of art of answer choices.