Program a Maze with Paper

1. Use a sheet of graph paper to create a small maze that fits on a rectangular grid. All of the maze’s walls should be vertical or horizontal – no diagonal or curved lines.
2. Start out with a small, easy-to-solve maze, and you can make a more difficult one later.
3. Make sure the maze has clearly labeled “start” and “finish” points.
4. Optional: you can also use a coloring or activity book that contains mazes, as long as it has some mazes with only vertical and horizontal lines.

1. Imagine that you are a person walking through your maze, starting at the “start” point. On a separate piece of paper, write down directions, one step at a time, for how you would walk through the maze. For example, use commands like “Move forward 2 squares,” “turn left,” and “turn right.” Continue writing directions until you have enough to reach the “finish” mark of the maze. Optional: if you prefer, you can draw arrows instead of writing out the words (a straight arrow for “move forward,” and curved arrows for turning).
2. Now, hand your maze, the directions, and pencil to your volunteer. Instruct them to follow your directions exactly as they go through the maze, even if they see a mistake. They are not allowed to solve the maze on their own or change the directions.
3. Watch closely to see if the volunteer successfully completes the maze by following your directions. Do they crash into any of the walls, or do they make it all the way to the finish line?
4. If your volunteer makes it all the way to the finish line, then congratulations! Your program did not have any bugs. Try making a bigger, more complicated maze, and starting over.
5. If your volunteer crashed into one of the maze’s walls, you need to debug your program. Carefully trace through your program step by step to see where things went wrong. Did you tell them to move one block too far, or turn one block too early? Just one mistake can throw off your entire program and cause a crash later on, so look carefully!
6. After you discover the bug, re-write your program. If you only need to change one or two steps, you can just erase them instead of re-writing the whole thing (this is one of the advantages of programming on a real computer – it is very easy to delete and re-write text!).
7. Have your volunteer try the maze again, following your new program. Can they solve it this time? If not, keep debugging your program until they can solve the maze.

Extra: computer programs are written in many different “languages,” which all have slightly different formats, but very similar underlying concepts. For example, some computer programs use punctuation and spelling differently – this is called the program’s “syntax.” For this project, can you come up with a different “language” that accomplishes the same task of solving the maze? For example, what about using commands that are defined relative to absolute directions on the piece of paper like “move up,” “move down,” “move left,” and “move right;” as opposed to turning left/right as if you were a person standing in the maze? Can you see how, although these two languages are different, they can both be used to do the same thing?

Extra: can you try the project with more complicated mazes that include diagonal or curvy lines? If you can no longer rely on a rectangular grid for movement, how would you write the program? Hint: try introducing new commands like “move forward until you reach an intersection” or “move forward until you hit a wall.”

Extra: instead of using a maze on paper, write a program to navigate a person walking through your house or school. Can they move from room to room without bumping into a wall by only following your directions?