Tap on the Smart TV located beside the green chalkboard. Choose a mini-game and play to complete levels. You will get rewards as soon as the game ends or when you lose all lives. You can also tap on the pause button and then quit the current game to earn rewards, but make sure you complete a few levels before quitting.
Some mini-games may require you to spend bus tokens to play them. The rewards you will receive from these games will be much more than the tokens spent.
You can also play a mini-game when a character is engaged in a fun activity. You will see a joystick icon beside the completion bar when you tap on a character who is doing a task. You can the play a mini-game to get additional rewards besides the rewards earned from the task he/she was completing.