Classroom Notes: Planning Solutions

• Algorithms: A clear set of step-by-step instructions designed to solve a problem or complete a task.
• Iteration (Loops): Repeating instructions in code to avoid writing the same line multiple times.
• Selection: Using conditional statements (IF... THEN... ELSE) to choose which path or instructions to run based on whether a condition is True or False.

A. Algorithm Efficiency

• Definition: An algorithm is efficient when it completes a task accurately by carrying out only necessary instructions without wasting time or computer power.
• Making Algorithms Efficient:
  • Using Iteration (Loops): Grouping and repeating common instructions instead of listing each one individually.
  • Using Selection (IF... THEN... ELSE): Checking conditions first so the computer carries out actions only when needed.

B. Decomposition

• Definition: Decomposition means breaking down a complex problem into smaller sub-problems that are easier to understand, plan, and solve.

C. The Four Building Blocks of Problem Planning

When planning computer solutions, break the problem into:

• Input: Data or instructions given to the computer by a user (e.g., entering numbers on a keyboard, typing an answer to a question).
• Process: Calculations, variable assignments, or data manipulations performed by the computer (e.g., calculating 5 + 5, assigning a user's typed reply to a variable like FavouriteAnimal).
• Condition: Questions or checks evaluated by the computer as True or False to decide what instruction to execute next (e.g., Is wake-up time equal to the current time?, Is Ground equal to SOIL?).
• Output: Information sent out of the computer system to the user after processing (e.g., displaying text on a screen, an alarm ringing, a chatbot saying a sentence).

D. Evaluation & Success Criteria

• Evaluation: Evaluation means checking if the program is meeting the success criteria (expected outcome).
• Success Criteria: Success criteria clearly defines what is expected out of the program.

An algorithm is efficient when it solves a problem in a careful, complete way using only the necessary instructions. This prevents any waste of time or computing steps.

A linear algorithm carries out every single instruction every time, regardless of the situation. Selection uses conditions (IF... THEN... ELSE) to check whether an action is needed, skipping instructions that are unnecessary.

Decomposition is breaking down a large, complex problem into smaller, simpler sub-problems. It helps programmers plan clear solutions by organizing inputs, processes, conditions, and outputs step by step.

• Input: Data given to a computer by a user.
  Example: Typing a wake-up time on a keyboard.
• Output: Information or actions produced by the computer system after processing.
  Example: An alarm ringing or text displayed on a screen.

A process is the set of steps carried out in order when a program or algorithm runs.
Example: An instruction or calculation, or assigning a typed answer to a variable.

Success criteria clearly defines what is expected out of the program.

Evaluation means checking if the program is meeting the success criteria (expected outcome).

User prompt is when the program is waiting for the input from the user.

System Step	Component
User sets / enters the target temperature (22°C) via the dial.	Input
The system stores the target temperature (22°C) into a variable.	Process
Checking IF RoomTemperature < TargetTemperature (22°C).	Condition
Heater switches ON (or remains off if False).	Output