When your school makes the move to mobile devices and buys a set of iPads it is important that you understand that setting them up in a school is different to setting them up for use at home.
At home you take your shiny new iDevice and connect it to iTunes. With iTunes and the app store you can share the apps you purchase between all of the devices you own up to a maximum of six. Apple also allow you to use Family Sharing so that other members of your family can share a single iTunes account. With Family Sharing its much easier for you to manage which apps your family have on their devices - particulalrly useful if you have young children with a device each as you only have to purchase their favourite apps once. You could even set up one device - save a backup to iTunes and restore it to another so that the apps and setup of both devices is identical.
Things are very different if you are a school. If you buy iPads for use in school you could technically use the same route as if you were a family but your apps wouldn't be licenced. Much in the same way as you can't use home licence for windows on your PCs.
In schools you must ensure that you have a copy of every app for every device that will have that app installed. The way you purchase apps is through something called the Volume Purchasing Program.
Once your school has registered for VPP and added your credit card details into the system you can purchase app licenses to use in school. The good news is that if you buy 20+ apps you will get them at a discount. This typically runs at around 50% of the original price.