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Communications of the ACM

Letters to the Editor

To Learn CS Principles, Start in the Cafeteria Line

Letters to the Editor


I enjoyed Thomas J. Cortina's Broadening Participation Viewpoint "Reaching a Broader Population of Students through 'Unplugged' Activities" (Mar. 2015) on teaching students computer science unplugged, that is, without a computer, especially the "parity bit" game puzzle, but would like to suggest yet another way to show students computer science principles in action, by leading them through their school cafeteria.

Many computer science textbooks explore the concept of a last-in first-out stack by comparing it to the stack of plates in the cafeteria. The plate most recently pushed onto the stack is always the next one taken off the top. Only the topmost plate is visible and accessible, as a spring platform causes the other plates to sink below counter level. Yet the plate-stack analogy is only the tip of the iceberg when it comes to computer science principles; for example, a queue of diners waits to be served, first in, first out, so after the person in front is served, each other waiting person is promoted to the next position in the queue. The conveyor-toaster demonstrates pipelining and the multi-slice toaster batch processing. When preparing, say, a bacon cheeseburger, rules of parallel processing apply. The grill cook can fry the bacon and grill a beef patty in parallel but must wait for both processes to complete before assembling the cheeseburger, a serial step.


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