Before the exam on Thursday 22 April, see what you can find about:

1) The order of evaluation of arguments to functions in Scheme.
   (Hint -- is this specified in the various Scheme Standards?)
2) What is a consbox or "cons cell" or conscell?  How are lists 
   actually stored in memory?
3) When are occurrences of variables "free"?  
   When are occurrences of variables "bound"?
   Where (in which part of an expression) are variables bound?

There will be questions on the exam related to these topics.

Don't forget to review Higher order functions