Algorithms Practice

These questions follow Algorithms in Everyday Life — and the literal-minded robot from The Sandwich Robot is watching.

Questions

1. Write instructions for making toast that would survive the most literal reading possible. Aim for six to eight numbered steps.
2. Match each description to a term — algorithm, variable, loop, condition: (a) a named box holding a value, (b) a precise list of steps, (c) a test that picks a path, (d) a repeat.
3. Predict the output. Trace the spoken algorithm “start at 1; while it is 20 or less, double it; say the number” — then as code:

   number = 1
   while number <= 20:
       number = number * 2
   print(number)

4. Find the bug in this hot-chocolate algorithm: (1) drink, (2) stir, (3) add cocoa to the mug, (4) pour in hot milk. Give an order that works, and name what kind of error this is.
5. A program finds locker 23 by checking locker 1, then 2, then 3, and so on. The lockers are numbered in order. Describe a better algorithm, and say roughly how much work it saves.
6. Challenge. Write a plain-language algorithm for finding the biggest of three numbers — precise enough to need no judgement.

Answers

Answer 1

Answers vary. The test: could a robot with no common sense follow it? “Put bread in the toaster” fails if the bag is still sealed — compare your steps with a partner’s and hunt for hidden judgement.

Answer 2

(a) variable, (b) algorithm, (c) condition, (d) loop. Using the right names is half of explaining any program clearly.

Answer 3

1, 2, 4, 8, 16, 32 — the check 32 <= 20 fails, so 32 prints. It sails past 20: the test happens before each double, not after.

Answer 4

One working order: 3, 4, 2, 1. The steps are fine — the sequence is broken: right instructions, wrong order, no crash, wrong result.

Answer 5

The lockers are sorted, so go straight to 23 — or leap in halves like Twenty Questions: 22 checks avoided out of 23. Ordered data is a gift; good algorithms accept it.

Answer 6

One version: call the first number the leader. Compare the second to the leader; if it is bigger, it becomes the leader. Repeat with the third. Announce the leader. No taste, no judgement — just steps.

Curriculum connection

C1.2

describe simple algorithms that are encountered in everyday situations

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C1.1

use appropriate terminology to describe programming concepts and algorithms

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