The standard symbols represent different types of steps in an algorithm: a diamond is a decision, a rectangle is a process, and a parallelogram is input/output. Arrows connect these symbols to show the sequence and direction of control.
Meaning of Each Symbol
In B1.1 Approaches to computational thinking, a flowchart is a visual representation of an algorithm. Using standard symbols makes the algorithm unambiguous and allows another programmer to follow its logic.
| Symbol | Meaning and use | Example |
|---|---|---|
| Diamond | A decision tests a condition and creates alternative paths. Each outgoing arrow should be labelled, normally Yes and No or True and False. | Is score >= 50? |
| Rectangle | A process performs an operation, calculation, or assignment. It changes data but does not ask for input or display output. | total = price * quantity |
| Parallelogram | An input/output operation either receives data from an external source or communicates data to the user. | INPUT name or OUTPUT total |
A decision must contain a condition that can be evaluated as true or false. For example, Is age >= 18? leads to two branches, while age = age + 1 is a process because it updates a value.
The common misconception is that every instruction belongs in a rectangle. User input such as INPUT password and displayed output such as OUTPUT result belong in parallelograms, not process rectangles.
Flowcharts also commonly use an oval or rounded rectangle for start/end and arrowed flow lines to show execution order. Every path should be logically connected, and each decision branch should eventually continue to another step or terminate.
Exam Technique
When asked to construct or interpret a flowchart, use the correct shapes, place one clear operation in each symbol, label both decision branches, and trace every possible path. Examiners reward accurate algorithmic logic as well as correct flowchart notation.
