If you’re looking to use Supervised mode on your iPads, you’ll find that Apple Configurator will re-install the iOS onto te devices as part of the deployment process.
For some schools with limited internet connections waiting while Configurator downloads the iOS version, and hoping that it succeeds and doesn’t experience some form of failure can be a frustrating experience.
Felix Bruns hosts a directory of the iOS software versions on his site at http://www.felixbruns.de/iPod/firmware/. From here you can download the .ipsw file for your device. Each version of the iPad, iPhone and iPod Touch seems to have its own .ipsw file, so make sure that you get the correct version.
Once you have downloaded the .ipsw file for your devices, when you are at the Prepare stage, choose Other.. from the iOS menu;
Then, use the + button at the lower left of the next screen to select the iOS Update file which you downloaded earlier.
Select the file you’ve added and click Done. You can now proceed to the next stages of deployment without Configurator needing to download iOS updates from Apple.