[plt-scheme] teachpacks vs. require

It seems to me that "require" can do anything that "Add Teachpack..." can do, and much more.  The biggest practical difference seems to be that the set of loaded teachpacks is remembered from one DrScheme startup to the next, regardless of what source file you're looking at, whereas "require"s are in source files.  Which makes a lot more sense.  Am I missing something obvious?  Is there any reason I should use teachpacks, other than ease of typing the first example on Day 1?

Stephen Bloch
sbloch at adelphi.edu