Quiz: Sorting Networks (CS Unplugged)

Instructions: Answer each question based on the "Sorting Networks" activity.

---

1. What is the main topic of this activity?
A) Writing computer code
B) Sorting numbers using a network where several comparisons happen at once
C) Learning to add large numbers
D) Playing a memory game with cards

2. How many people are needed for one team in this activity?
A) Two
B) Four
C) Six
D) Eight

3. What do you do when you arrive at a circle (node) in the network with another player?
A) Add your numbers together
B) Compare cards — the smaller number goes left, the larger goes right
C) Swap cards with your partner
D) Sit down and wait for the teacher

4. What happens if a team makes an error while going through the network?
A) They lose a point
B) They swap cards and try again
C) They must start again
D) They skip to the end

5. According to the activity, why do computer scientists use several computers to work on a problem at the same time?
A) To make the problem harder
B) To solve problems faster
C) To use less chalk
D) To avoid comparing numbers

6. In the six-number sorting network, how many comparisons are used in total?
A) 5
B) 6
C) 10
D) 12

7. Because some comparisons happen at the same time, how many comparison "steps" of time does the six-number network actually take?
A) 3
B) 5
C) 8
D) 12

**8. In the ditch-digging analogy, why can't ten people finish a ditch that is ten metres deep much faster than one person?**
A) There isn't enough room for ten people to dig at once
B) Each metre must be dug before the next one can be reached, so the work can't be split up
C) Digging deep ditches requires special tools
D) Ten people would get in each other's way on the surface

---

Short Answer Questions

9. In the sorting network activity, what happens at each circle (node) — explain what a player must do when they meet another player there.

10. Explain what would happen if, at each node, the rule were reversed so that the smaller number went right instead of left.

11. Using the ditch-digging example from the resource, describe the difference between a task that can be sped up by working in parallel and a task that cannot.

---

Answer Key

1. B
2. C
3. B
4. C
5. B
6. D
7. B
8. B
9. When two players meet at a circle, they compare their cards. The player with the smaller number takes the exit to the left, and the player with the larger number takes the exit to the right.
10. The numbers would come out sorted in reverse order.
11. A task like digging a ditch that is long (spread out) can be split among many people working side by side, so it goes faster with more workers (like digging one metre each). A task like digging a ditch that is deep cannot be sped up this way, because each part depends on the part before it being finished first (the second metre isn't accessible until the first is dug), so parallel work doesn't help.