TeachScheme! 2000

 Introduction to the Scheme evaluator project: 

  What is the core of DrScheme? (relate to views of data from Monday)

  Why need a model for expressions?
  -- why can't they write eval and use as (eval (+ 5 9))?

  Work through data defn for arithmetic exps + symbols

  Do examples of eval on examples of data defn

  [send to lab without doing template -- they can handle the template
   by this point]