The National Institute of Environmental Health Sciences, Squigly's Fun Brain Teasers and Fun With Puzzles each offer several brain teaser questions on their websites. Each site allows you to view the answer to each brain teaser question.
The National Institute of Environmental Health Sciences includes brain teaser questions in several quizzes designed for kids. The correct answer is provided in a drop-down list with other options. Squigly's Fun Brain Teasers allows users to click to have the answer shown; the answer is provided with a complete description. Fun With Puzzles provides several challenging brain teasers and also includes descriptive answers at the bottom of the page.