First readers: 
  Christos: Thursday, Friday after noon; Stephen Friday morning 
  Felix 

MAX TOTAL CREDIT: 20

STYLE and TEST-RUN points: 5
 -- does the program run (1) and cover almost all of the program (2)
    remember that we tell students to put big-bang into a main
    function and they don't have to test it
 -- does the program satisfy the style points (2)
    http://www.ccs.neu.edu/home/matthias/107-f09/Assignments/style.html

CODE CREDIT: 10
 -- data definitions: represent & interpret (2)
 -- for functions, did they follow the design recipe process, 
      did they match the structure (6)
 -- did they design auxiliaries (2)
 
PRESENTATION: 3 
 -- did they follow the process to present functions (2) 
 -- can they recover from questions, mistakes 

PARTNERSHIP: 2 
 -- the students receive the average of their style, code, and 
    presentation scores, plus 2 unless their scores differ 
    by 6 or more points (e.g., one gets 13 and the other gets 7, then
    they receive 10 points total) 

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I have chosen the following two problems, and I supply minimal notes on
design and correctness: 

1.2: HtDP/world design: 
 -- data def for WorldState 
 -- constant definitions for size (and perhaps colors)  
 -- at least two event handlers: 
    ++ on-draw
    ++ on-key
    ideally, the program should also include a stop-when predicate 
    (see language on 'final' in exercise); point students there
    each handler follows design recipe; an on-tick handler suggests
    copy-and-paste coding (not thinking) and requires deductions 

1.3: plain HtDP design, follow the recipe for Expr, nested if
     plus factoring out auxiliary functions 
     because of repeated separate tasks 
     -- image-append for text images 
     -- parenthesize, because the problem statement mentions it 
     both aux functions are compositions (of primitives)