In the K-12 level there are two sites that a student might use in the Kindergarten, Arithmetic and Geometry. Arithmetic had leveled problem puzzles and Aims activities in math. Geometry had Ask Dr. Math with questions and answers about numbers and geometry. Students can submit their solution to the problem by the following Monday. The site has colorful balloons that mark information that you might need to submit your answer.
Mentors check each problem answer submitted.
Students that get the correct answer will be listed on the web site. Mentors will choose a number of solutions to highlight. These highlighted solutions will appear with comments from Mentors. The use of these sites by a Kindergarten student would most likely have to be with an aide or peer helper. Ideally it would be a time for upper grade students in the gifted and talented, to work with a younger students.