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Sorting Networks (CS Unplugged)

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Sorting Networks (CS Unplugged) — Flashcards

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What is a sorting network?A system of comparisons (used by computers) that sorts numbers, where several comparisons can be done at the same time.
What is the main idea behind "Beat the Clock—Sorting Networks"?Even though computers are fast, using several computers to solve parts of a problem at once (parallel processing) can speed up solving problems like sorting.
What happens at each circle (node) in the sorting network?Two people meet, compare their number cards, and the person with the smaller number exits left while the person with the larger number exits right.
How many people are needed for the six-number sorting network activity?Six people, each holding one numbered card.
What must you do if your team makes an error in the network?Start again from the beginning.
What are the materials needed for this activity?Chalk, two sets of six cards (Photocopy Master), and a stopwatch.
What happens if the smaller number goes right instead of left (and vice versa)?The numbers will be sorted in reverse order.
Does the sorting network work if used backwards?Not necessarily — there can be inputs that come out in the wrong order.
What is serial processing?A method where all comparisons must be done one after another, one at a time.
What is parallel processing?A method where several comparisons (or computations) are performed at the same time, making tasks faster.
In the six-number sorting network, how many comparisons are used in total, and how many steps does it take?12 comparisons total, but only 5 steps are needed since up to 3 comparisons happen simultaneously.
How can a sorting network be used to find a minimum or maximum value?By designing a network where only one output remains (the minimum or maximum), while other values are left at dead ends.
What is one way to make computers process information faster?Writing programs with fewer computational steps, or using parallel processing with multiple computers.
Why can't all tasks be sped up using parallel computation?Some tasks depend on previous steps being finished first (e.g., digging a ditch 10 metres deep — you can't dig the second metre until the first is done).
What is an example of a task that CAN be sped up with parallelism?Digging a ditch 10 metres long — ten people can each dig one metre at the same time.
What curriculum skills does this activity develop?Comparing, ordering, developing algorithms, and co-operative problem solving.
What ages is this activity designed for?Ages 7 years and up.
In the four-input sorting network comparison, which type is faster and why?The parallel network is faster because some comparisons are performed at the same time, instead of all being done serially one after another.

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