Understand how to create a more realistic application using the tools we already have,

Know how to use the switch statement to select among a number of alternatives,

Know how to use the enum data type to give names to constant values that will be used to refer to items in a list,

Understand the advantages of creating variables at the point of use rather than at the beginning of a function,

Know how to find or change the size of a Vec dynamically when necessary, and

Understand how to use virtual functions for implementation purposes within a polymorphic class hierarchy.