[charlieok]

I'm surprised that a whole class of kids who were not deaf knew enough sign language to convince the author that they were deaf.

[johnpowell]

I took a year of sign language in high school to satisfy the language requirement. This is the sort of thing I could imagine a instructor doing. It was a public school so our outing would have probably been to Burger King.

[WiseWeasel]

They only needed the first one to be somewhat convincing; the rest were probably an easy sell.