Move your math lesson into the outdoors with this fun math activity. ‘Ring the GCF’ is a simple game that is perfect for making GCF practice exciting. Kids race to be the first to ring the correct GCF each time a pair of numbers is called out. At the end of the game, the player with the highest score wins. Studies have shown that kids remember a lesson better when it is associated with physical activity. Use this outdoor math game to help your fourth graders practice GCF. The game is ideal for small groups of 4 to 5 players.