Welcome to Android Central! Is it your home wi-fi network, or somewhere else (like school)? Can she access websites without problem using the browser? Is the wi-fi icon in the Notification Bar grey or blue? With Android versions below KitKat, blue means there is a connection to the Google server, while grey means no connection. Connection problems might be due to issues with the Google servers on their end, or problems on your end--but if you can access other parts of the internet, it's probably not on your end.
There has also been a few glitches lately in the Google Play Store--how long has this problem been going on for your daughter? Give it a day or so, and try again.