Hi Carol,
You are right on the spot with respect to the jr.jar being a zipped up package of directories, and if you unzipped it, it would make the paths you describe.
So as long as you have the jr.jar file in your CLASSPATH, your programs should be able to use anything that is inside it. On my own computer, the .jar files have to be specified specifically (gee - so articulate today), whereas if you have .class files, it is enough to specify the directory within which they reside. So for .class files:
/home/katrina/java/classes/
and for jr.jar:
/home/katrina/java/jars/jr.jar
Or something to that effect.
I can't promise that what I just told you is technically true - it just coincides with the way I make sense of it
Katrina