What is a good 10 to 20 hour program-to-write for a new VB.NET programmer that utilizes inheritance?

Question

I'd like to give a homework assignment to a person learning VB.NET.

I'd like it to use basic inheritance and a variety of data structures including queues, lists, arrays, or stacks in a windows forms application.

I was thinking of a pizza-ordering application. This would allow them to utilize some basic inheritance and practice using .NET UI elements.

Any ideas?

Thanks

Edit: Knowledge Level of Programmer: Basic, uncomfortable grasp of data types, data structures, inheritance.

Answer 1

I did a moonphases thing for one of my projects.

Nice small model. (moonday, moonmonth)

In short show the current moonphase. And show the moonphases per day for that month and for all the days of that year. Extra points for finding the first blue moon month.

Kinda fun.

Answer 2

Have them write a timer/alarm clock application that can sit in the tray and alert people at intervals, or at a specific time, or after a duration.