The Aquarium Lab Series    

The Aquarium Lab Series is a series of mixed-length laboratory exercises that provide students with an opportunity to put introductory programming concepts to work immediately. Thus, the series is meant to be used very early in an introductory course on programming in C++. The labs were developed to support an objects-early curriculum in which students learn to read interfaces, construct objects, and invoke member functions immediately after learning how to use primitive types. Students learn how to use basic control structures (if statements, for loops) and vectors in the context of writing client code, before learning how to implement classes and write member functions.

The labs in this series were inspired by the Advanced Placement Computer Science Marine Biology Simulation Case Study, available from the College Board. These labs, however, are meant to be used even earlier in the school year, as students learn about constructing objects, using if statements and for loops, and calling functions.

Some of the classes used in the Aquarium Lab Series are the same as, or very similar to, those in the Marine Biology Case Study (for example, RandGen and Display). Others are considerably different from the case study. WARNING: the similarity in names (particularly the AquaFish class) may create confusion for some students who use both the Aquarium Lab Series and the Marine Biology Case Study. Others will have no difficulty, particularly if teachers point out the differences between the two.

The Aquarium Lab Series consists of two full-length labs, which need approximately two hours to complete, several mini-labs, which can generally be completed in less than an hour (sometimes considerably less), and several supplementary assignments.

Starting Code:

• Main function
• AquaFish class (header file and implementation file)
• Aquarium class (header file and implementation file)
• Display class (header file, text-based implementation file, and graphics implementation file)
• RandGen class (from Marine Biology Case Study -- header file and implementation file)
• Utility functions (header file and implementation file)
• WaitNClear function (header file and implementation file)
• GNU General Public License

  NOTE: Teachers may wish to download the starting source files in advance, create a project or makefile, and then provide these materials to students as a unit.

Mini-Lab: Reading Interfaces and Writing Client Code
    (recently modified, the previous version is still available: Reading Interfaces and Writing Client Code)

Tasks include:

• Read several class interfaces.
• Write client code to construct objects and invoke member functions:
  • Modify the main function to construct three fish in the aquarium.
  • Display the fish in the aquarium.
  • Move all three fish one space.
  • Redisplay the fish in the aquarium.

Pre-Lab Assignment: Experimenting with the CMU Graphics package and
Full-length Lab: Displaying the Aquarium Using Graphics

Tasks include:

• Experiment with the CMU Graphics package⁺ (run a demo and make a trivial change to some existing code).
• Modify the CMU "house" demo to create an aquarium instead.
• Transfer the code to create an aquarium to the program created in the previous lab.

Mini-Lab: If Statements

Tasks include:

• Have each of the three fish change direction if they are about to hit an aquarium wall.
• Change the way that fish are constructed to give each one an initial color.
• Display each fish using the appropriate color.

Mini-Lab: For Loops

Tasks include:

• Prompt the user for how many time steps the simulation should run.
• Run the simulation of fish moving and changing direction for the right number of time steps.
• Modify fish movement so that in each time step a fish randomly chooses whether to change direction (unless it is about to hit a wall, in which case it always changes direction).

Supplementary Assignment: A Few More Enhancements

Tasks include:

• Add support for more colors.
• Use the Pause command to allow the simulation to run continuously rather than requiring a mouse click to move on to the next time step.
• Give the fish a one-in-four probability of changing direction rather than a one-in-two probability.

Related Full-length Lab: Creating a Histogram

Tasks include:

• Add a loop to run a simulation of fish movement 1000 times.
• Keep track of how many times the fish ended up in each of several possible final locations.
• Draw a histogram of how many times the fish ended up in each of the final locations.

Mini-Lab: Vectors

Tasks include:

• Prompt the user for how many fish they want in the aquarium.
• Construct a vector of the right number of fish.
• Replace the "default" fish in the vector with properly initialized fish.
• In each time step, move and display all the fish.
• Correct the fish movement logic so that fish at a wall cannot change direction and swim out of the aquarium.

Related Supplementary Assignment: Adding Vectors to the Histogram Project

Tasks include:

• Replace series of variables representing final counts with a vector.
• Replace series of conditional statements with a single statement using an arithmetic expression to index the vector.
• Draw all the bars of the histogram in a loop.
• Add a title and other clarifying information to the histogram.

Supplementary Assignment: Even More Enhancements

Tasks include:

• Add code to allow fish to ascend and descend.

^*This lab series was inspired by the Advanced Placement Computer Science Marine Biology Simulation Case Study.

⁺The CMU Graphics Library was created by the Carnegie Mellon University School of Computer Science and is used in their introductory programming courses. It is available from Mark Stehlik's Advanced Placement page.