My son joined his school's math club this year and competed in the BAE Systems Mathalon. Math clubs from area schools gathered and competed against each other. My son's team didn't win but it was a great experience for him. All those who competed received a participation certificate.
If you missed my other December Picture Post-A-Thon posts here are the links:
December Picture Post-A-Thon Begins: Vegas 2016
December Picture Post-A-Thon Continues: Fall 2016 Apple Picking