Flowchart Symbols: A Visual Guide

Master the language of algorithms. From ovals to diamonds, learn how to draw logic that speaks volumes.

Why Visualise Logic?

The Power of Flowcharts: A diagram can explain nested loops and complex decisions in a single glance that would take pages of text to describe.

Standardization: We use ISO (International Organization for Standardization) symbols so a programmer in Jamaica can read a chart designed in Japan without confusion.

Text to Shape Challenge

Read the instruction below. Click the correct shape that represents it!

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Start

Read

Calc

If?

Score: 0/5

The Essential CSEC Symbols

Terminator

Oval

Used for the START and STOP. Every algorithm needs exactly one of each.

Input/Output

Parallelogram

User interaction. READ data or PRINT results to the screen.

Process

Rectangle

Internal calculations or assignments. Total = A + B.

Decision

Diamond shape for IF/THEN. Has 1 entry and 2 exits (Yes/No).

The Flow of Data: Directional Arrows

The "Glue": Arrows connect the shapes. They show the exact order of execution.

Direction: Generally Top to Bottom, or Left to Right.
Crossing: Arrows should never cross if it can be avoided.

Arrow Director

Click the dashed boxes to draw the arrows and connect the logic!

➕

Representing Control Structures

1. Sequence: The simplest structure. Instructions are executed one after another in the exact order they appear, like a straight line of dominoes falling.

2. Selection (Decision): The program asks a question (Condition) and chooses between two paths. If the answer is Yes, it goes one way; if No, it goes the other. This is controlled by the Diamond symbol.

3. Iteration (Looping): A specific set of steps is repeated over and over. The flowchart shows this by drawing an arrow that points backwards to a previous step (usually a Decision Diamond) to restart the process until a condition is met.

Structure Identifier

Identify the logic structure shown in each diagram.

From Pseudocode to Flowchart

The Live Translator

Click a line of code to reveal its matching flowchart shape!

START program

PRINT "Enter Name"

READ UserName

SET Age = 18

IF Age > 18 THEN...

CSEC SBA Prep: Professional Drawings

Tool Recommendations

Don't use Paint! Use proper tools like Lucidchart, Draw.io, or even Microsoft Word's SmartArt/Shapes.

Common Mistakes to Avoid

❌ Writing full sentences inside shapes (keep it brief).
❌ Forgetting to label "Yes/No" branches on decisions.
❌ "Dead Ends" where arrows stop in the middle of nowhere.

Knowledge Check: Symbol Master

Quick Quiz

Which shape for "Calculate Discount"?

Fix the Flowchart

Click the wrong shapes to fix them!

CSEC Practice Question

Question: Write an algorithm to accept Cost of an item from a user.

If Cost is greater than $100, calculate a 10% discount and display New Price.
Otherwise, simply display Original Cost.

Solution Flowchart

Here is the visual representation of the algorithm.

Key Steps Explained:

1. Input: Use a Parallelogram to get Cost variable.

2. Decision: The Diamond checks the condition > 100.

3. Yes Branch: If true, a Rectangle calculates NewPrice = Cost * 0.9.

4. No Branch: If false, NewPrice just equals Cost.

5. Merge: Both paths meet before output to avoid two separate PRINT instructions.

6. Output: Display result using a Parallelogram.

Challenge Question: The Loop

Question: Write an algorithm to print even numbers from 2 to 10.

Iteration Flowchart

Notice how the arrow loops back to create repetition.

Loop Mechanics:

1. Initialize: Set Count = 2 to start at the first even number.

2. Test: The Diamond checks if we have reached the limit.

3. Body (Yes): If true, we PRINT the current number.

4. Update: Increment Count by 2 (to get the next even number).

5. Loop Back: The arrow returns to the decision to check the condition again.

6. Exit (No): When Count becomes 12 (not <= 10), the loop breaks and we STOP.