Some POW links
Here are a few sites that offer problems of the week for various levels, starting at (upper) elementary level:
- Columbus State University — they accept submissions of numerical answers, and publish the names and schools of correct submitters. They don’t post solutions, but they will send you a solution for a past problem if you request it.
- WhiteHouseKids.gov (their problems are at least in part provided by Colorodo State, so they may overlap with those above) — they don’t post solutions, but they have a type-in box where you can check your answer.
- EduPlace.com offers 3 separate puzzles each week — for grades 3/4, 5/6 and 7/8. They publish solutions for each puzzle the next week.
All of these sites also provide an archive of past problems.