Yes, super powers!

I went to a high school where the drama department did at least one play a year in ASL. Brought in instructors from the local deaf community, and all the drama kids learned it.

This was also business genius, because it basically guaranteed ticket sales. A huge number of deaf people in the area would show up for every such play, year after year. Even parents with kids at the school generally stop coming to plays after their kids graduate, but this audience was loyal on the scale of decades.

It also meant that a significant chunk of the student body was now able to communicate in/across a noisy room. During assemblies and stuff, you'd see a dozen conversations in progress, not making a sound.

Or, communicate near-silently. Clothes rustle and certain signs involve patting, but neither of those sticks out the way voices do. Coordinating a prank behind the teacher's back....

god this sounds awesome

A risky habit: signing with other deaf drivers on the motorway. I've done it...

I've seen people doing that on the highway, too! It appears to generally be one gesture, and occasionally the horn is used for greater emphasis.

Braille books are quite expensive though, aren't they? Did they already have braille books around the house for someone else?

They might have checked them out from a public library.

To the extent that these are related, it's because of disability.

Braille is just a writing system. Signed languages are generally not.

Isn't that what flashlights are for?

Way easier to hide. If you were brave enough, you could literally read braille under the covers with your eyes closed while your parent had their head stuck through the door to check on you.