---
title: "Writing an Algorithm Down: Flowcharts and Pseudocode"
description: "An algorithm can be recorded before any code exists, as a flowchart or as pseudocode. Both fix the order, the decisions and the repetitions, so the plan can be checked on paper and argued about with s"
canonical: https://lightmysky.com/learn/computing/writing-an-algorithm-down-flowcharts-and-pseudocode-mt_RCm-4b4Lof
source: https://lightmysky.com/learn/computing/writing-an-algorithm-down-flowcharts-and-pseudocode-mt_RCm-4b4Lof.md
retrieved: 2026-09-12
---

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# Writing an Algorithm Down: Flowcharts and Pseudocode

An algorithm can be recorded before any code exists, as a flowchart or as pseudocode. Both fix the order, the decisions and the repetitions, so the plan can be checked on paper and argued about with someone else.

Subject: Computing · Area: Computing Fundamentals · Ages 13 to 14
Page: https://lightmysky.com/learn/computing/writing-an-algorithm-down-flowcharts-and-pseudocode-mt_RCm-4b4Lof

## Ready when they can

- Draw a flowchart for a task with at least one decision and one repetition, using the right shape for each
- Write the same algorithm as pseudocode and show the two agree step for step
- Find a missing or out-of-order step by walking the flowchart with a test value

## Lesson: Plan it on paper first

An algorithm can be recorded before any code exists, as a flowchart or as pseudocode, like the strange programs you just read. Both fix the order, the decisions, and the repetitions. A plan on paper can be checked with a friend long before any code runs.

**Example.** Pseudocode writes the plan in plain words, one short command per line, with capitals for actions. To ask for a password until it is right: ASK the user for the password. WHILE the password is wrong, ASK again. PRINT welcome. Indent the lines inside the loop so the repeat shows.

A flowchart draws the same plan with shapes. Ovals mark start and end, rectangles hold actions, diamonds hold decisions, arrows fix the order. The password loop becomes: ask, then a diamond asking if it is right, with a no arrow looping back to ask. Both forms must agree step for step.

Walk the plan with a test value, doing exactly what each line says. Try a wrong password first, then the right one. A missing ASK inside the loop, or two steps in the wrong order, shows up at once on paper.

**Recap.** Write the steps in plain words or shapes, then walk them with a test value.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Reading a Program Someone Else Wrote](https://lightmysky.com/learn/computing/reading-a-program-someone-else-wrote-mt_VdxhuxjBSn)

## Opens up

- [Variables and Assignment in Text Code](https://lightmysky.com/learn/computing/variables-and-assignment-in-text-code-mt_uLHLaX8BQq)