Hi Jessica,
Welcome back! It is great to hear from you again! There are indeed companion restrooms located in all four of the theme parks, both water parks and the ESPN Wide World of Sports. You can see a list of the locations on-line by visiting the section for guests with disabilities (click
here). Then scroll down to the link for
Restrooms for Guests with Disabilities at Walt Disney World to see a list of the companion assisted restroom locations. These locations will also be marked in the Guide Map that you can pick up when you enter a park.
Having traveled with my kids a lot, I've learned that it is important to scout out the restroom locations ahead of time. Tell the parents to make sure they plan ahead. There are several locations in the parks but there is usually only one companion restroom at each of the locations and it may take awhile to get in on days when the parks are very crowded.
On my last trip, there was both shower gel and bars of soap in my room. I'm not sure if it is available at every resort without requesting it. Make sure you ask when making reservations. You could also contact MouseKeeping (don't you love how Disney gives cool names to everything?!) when you arrive if there isn't shower gel in your room.
It is so awesome that you care enough about your students to help them outside the classroom as well. I'm looking forward to hearing from you again. Oh yea, have a magical day! :-)