For a classroom environment, you can consider both Cinch and DexterOS. Cinch will give you Scratch but not Bloxter, DexterOS will give you Bloxter, but not Scratch. Both will offer Python.
The one trick that is the most important one to avoid interference is that each GoPiGo must have a unique name so you will have a bit of prep time in assigning a unique name to each. We’ve had teachers use dog breeds, or car makes so the kids can relate to their GoPiGo instead of just using numbers but it’s entirely up to you.
If you have the Pi3, then you can use the wifi that comes onboard. We recommend the DexterOS dongle as it seems to be more stable than the Pi3 wifi but many people don’t have any issues with the onboard wifi.