[plt-scheme] trace

I'm playing a bit with trace, to see if I want to use it in classroom 
demos. I made a teachpack ("module trace mzscheme") that makes it 
accessible to Intermediate Student. But when I trace a function 
consuming structures (the parent structures from the descendant family 
tree example of HtDP), it doesn't show the inside of the structures, 
only #<struct:parent>, even though typing the name of a structure-valued 
variable in the REPL gives me a (make-parent ...) expression. Is there 
any way to get it to do this? I'm guessing it has something to do with 
inspectors, which I don't really understand. Many thanks. --PR