Push the "On/Off" button on your LeapFrog Tag Junior or Tag reader to turn it off.
Hold the Tag with the back facing you and look for a screw.
Push in on the screw with a flat-edged screwdriver, or the edge of a small coin, and turn the screw counterclockwise to unlock the battery compartment cover.
Remove the battery compartment cover from your Tag and set it aside.
Insert two new AAA alkaline batteries so that the polarity marks on the batteries match the marks inside the compartment. If you have the Tag Junior, push and hold the tab marked with an arrow in the direction that the arrow points, insert the batteries, then release the tab when finished.
Return the cover to your Tag. Secure the cover by turning the screw clockwise until you meet resistance.