Topics that We Should Review 

* The components of an algorithms [Sam]
* Scheme's basic syntax and program model
* Our first data type: Colors 
  * Ways to talk about colors
  * Standard procedures for making and manipulating colors
* A related data type: Images
  * Images as grids of pixels
  * Basic image operations
* Looping through images
  * image.map
  * image.map!
  * region.compute-pixels!
* Detour: Positions, another data type
* Functions
  * Defining your own
  * How they work
  * Using anonymously
* Numbers and numeric procedures
* Conditionals: Making Choices
* Lists: Collecting data
  * Basic operations
  * Iterating over lists
* Spots: Our own data type
  * Design
  * Key procedures
* Recursion