[plt-scheme] writing teachpacks

I'm not having much luck in v4.0.

In the Module language, I save the following in io.ss:

#lang scheme

(provide read)

I then switch to a new window, switch to Beginning Student, try to add 
this as a user-installed teachpack, and get the dreaded:

Users/plragde/Library/PLT 
Scheme/4.0/collects/installed-teachpacks/io.ss:1:0: compile: bad syntax; 
function application is not allowed, because no #%app syntax transformer 
is bound in: (module io scheme (provide read))

This seems to happen to me in 3.99.0.23, so I'm sorry that I didn't try 
it earlier. --PR