What's taking up all the storage on my iPad?

When I look at usage the individual apps add up to about 2 GB but it says I've used about 11 GB. What is taking up so much space. It's my school iPad so I'm not allowed to upgrade the iOS to see the ar representation in setting and I also can't plug it into a computer to look st the storeage in iTunes because its restricted. It's very annoying because I have barely anything on this iPad and less than 400 MB of space.
Added (1). It's and Air 2 and I've had it for 2 and a half years of that helps
Added (2). *if

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I'm connected to the wifi, but when I try to update my iPad to 10.2, it says I'm no longer connected to the Internet when I have 3 bars

Honestly every time I try to update, it verifies for a few seconds and goes on to say no longer connected to the Internet. How will I be able to update my iPad without getting these prompts, or how can I update successfully?
Added (1). Still need help on this

Read more: I'm connected to the wifi, but when I try to update my iPad to 10.2, it says I'm no longer connected to the Internet when I have 3 bars