[plt-scheme] A Couple of Questions on DrScheme/Mzscheme

P.S. For European readers, three lectures at Rice mean "one week" or three
times 50 mins. So I meant in 1 week out of 15 cover all of Part I, 
in the second week, recursive data and recursive functions incl the 
beginning of mutually recursive data/functions. 

For American readers, I have to say this because my lectures in Germany
were close to 2 hours in one setting per week in many instances.