Apple is releasing iOS 8, the next major version of the iPad/iPhone software, on Wednesday night, 17th September. Read all about it here.
For school's using Apple Configurator, it would be wise to prepare for this release, as you might not want all your iPads upgrading before you are ready.
So, before Wednesday night, ensure Configurator is set to "Never Update device" as shown in the picture below. You will need to sync your iPads to Configurator, so they get this setting change before Apple releases iOS 8.
If you do not do this, next time to connect your iPads to Apple Configurator, even to add just one app, the iPads will be updated to iOS 8 – which may not be the best plan until the dust settles on the update.
When you are ready to update your iPads to iOS 8, simple change the "Update iOS" menu to "When Update is Available" and click Apply/Refresh for ONE iPad. Once you checked that it's all OK, then you can do the rest of your iPads.