Offline playing allows players to continue playing in situations, in which network connection is not reliable and players can lose connection from time to time. If player is offline, videos and audio can't be played or used as answer methods. Answers are stored in the browser's temporary memory (cache) and sent to teacher when player is back online. Sometimes memory can get full and the game freezes, leading to losing all answers. It's good to note that if you're using levels, player can't get to next level while they are offline. We recommend going online regularly.
Activate offline mode from game settings and save.