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THUMBNAIL:

AUDIENCE/ CONTEXT:

FORCES:

Many applications of computer science are very complex and outside the skill level of novices to absorb completely.

While we are teaching programming, it is nice to let the students program with things that will teach them some simple ideas from courses that they will encounter later in the curriculum.

Students have to program with "something." Often it is just integers and floats at the beginning. It could be things more exciting to them and which teach them on a variety of levels simultaneously.

SOLUTION:

Student exercises are chosen to give the students a rich set of experiences about what can be done and what is important in computer science. These exercises are supported by a library of instructor provided materials that make learning fun.

Students are given a library of classes that can be used to implement some complex functionality. These are the building blocks. They then use them to build some artifact. Instead of programming with integers and arrays, they program instead with logic gates, for example.

The instructor distributes a class library that implements the basics of some functionality. The students may either use this unchanged or extend it and use the extended version to build some project. Care must be taken that the hierarchy is soundly built, demonstrating excellent techniques, and excellent structure.

DISCUSSION/ CONSEQUENCES/ IMPLEMENTATION:

This pattern allows students to actively work with larger programs than they can develop completely themselves. If the tools are chosen correctly, they can also gain breadth of understanding of the entire field. If the class hierarchy is well built it also serves as a good model for students building their own classes and hierarchies later, though the intent is not to teach OOP specifically.

SPECIAL RESOURCES:

RELATED PATTERNS:

• This pattern can be used to provide examples for cycles around a Spiral.
• A collection of these can be Larger Than Life, especially if closely interrelated.
• A well chosen collection could also demonstrate Lay of the Land .

See Also: Fixer Upper, Spiral, Mistake, Early Bird, Toy Box, Tool Box, Lay of the Land, Test Tube and Larger Than Life as a pattern language.

EXAMPLE INSTANCES:

An assembly language simulator that lets students get familiar with goto/register programming without all the details of a real machine.

An extension to the above that shows some of the problems with concurrency. A set of classes that let students experiment easily with readers/writers conflicts, for example.

A simple game with complete information that plays against the user but learns from its mistakes.

A simple spreadsheet like program. The program can store "programs" in cells using the simple assembly language of earlier "toys".

A set of classes implementing a simple relational database that can be queried with a simple language.

Some of these things are complex, but with appropriate scaffolding, even beginning students can use and extend the tools appropriately.

Decker & Hirchfield's Analytical Engine is a good use of this pattern.

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