Charging your Sphero is really easy, but it does take a few hours to charge from a completely dead battery, so leave yourself some time before a planned lesson to check your robot and recharge it if necessary.
The charger cradle is round, bright blue, and cupped to fit your Sphero ball. Make sure the cord is securely plugged into the back of the cradle, plug the cord into your outlet, and plop Sphero into the cradle. While Sphero is charging, the blue light on the front of the cradle will flash slowly, and once Sphero is charged the light will glow a solid blue.
Charging usually takes between 30 minutes to 2 hours, depending on how depleted the battery is. We recommend checking Sphero with enough time before your lesson to charge it up if the battery is low. We also suggest you charge Sphero for a little while after your lesson, so it goes back into the BOX ready for the next teacher!