Primary 3 (Stage 3) – Study Notes: Computational Thinking

What is an algorithm?

• A) A type of computer

• B) A clear, step-by-step instruction to solve a problem or complete a task

• C) A kind of software

• D) A random guess

Answer explanation

An algorithm is defined as a clear, step-by-step instruction to solve a problem or complete a task, making option B the correct choice. The other options do not accurately describe what an algorithm is.

Fill in the blank: A linear algorithm is a list of steps that run one after another in _____

• order

• reverse

• random

• parallel

Answer explanation

A linear algorithm executes steps sequentially, meaning they run one after another in order. This is why 'order' is the correct choice, as it reflects the structured flow of a linear process.

Which of the following is an example of a linear algorithm?

• Brushing teeth: Put toothpaste on toothbrush → Brush teeth for 2 minutes → Rinse mouth with water

• Jumping randomly

• Guessing answers

• Skipping steps

Answer explanation

The correct choice, 'Brushing teeth,' is a linear algorithm as it follows a clear, sequential process: applying toothpaste, brushing, and rinsing. The other options lack a structured, step-by-step approach.

An efficient algorithm solves the problem with _____

• The most complicated steps

• The fewest and clearest steps

• The longest list of steps

• Random steps

Answer explanation

An efficient algorithm is characterized by solving problems using the fewest and clearest steps, minimizing complexity and maximizing clarity, which leads to better performance and easier understanding.

Fill in the blank: Many activities have patterns or _____

• repetitions

• colors

• numbers

• shapes

Answer explanation

The correct choice is 'repetitions' because many activities involve repeating certain actions or patterns, making 'repetitions' the most fitting word to complete the sentence.

Which of the following is an example of repeated steps in an everyday task?

• Making sandwiches: Spread → Add filling → Close → Repeat for next sandwich

• Doing nothing

• Skipping steps

• Guessing the next step

Answer explanation

The correct choice, making sandwiches, illustrates repeated steps: spreading, adding filling, and closing, which are consistently followed for each sandwich. This exemplifies a clear sequence of actions in an everyday task.

What is a linear algorithm?

• Steps done in random order

• Steps that repeat forever

• Steps done one after another in order

• Steps that never end

Answer explanation

A linear algorithm consists of steps that are executed sequentially, one after another in a specific order. This ensures a clear and predictable flow of operations, making it distinct from random or infinite processes.

What does a linear algorithm do?

• Jumps between steps

• Repeats steps randomly

• Follows steps from start to finish in a set sequence

• Skips steps

Answer explanation

A linear algorithm processes steps in a specific order, moving from the beginning to the end without skipping or jumping around. This ensures a clear and predictable flow, making 'Follows steps from start to finish in a set sequence' the correct choice.

Which step is missing?

• 3. Apply soap

• 1. Turn off the tap

• 2. Dry your hands

• 4. Shake hands

Answer explanation

The missing step is '3. Apply soap', which is essential for effective handwashing. It should occur after turning off the tap and before drying hands, ensuring cleanliness before any further actions like shaking hands.

Why do we edit algorithms?

• To make them colorful

• To make them longer

• To fix errors or improve them

• To make them look fun

Answer explanation

We edit algorithms primarily to fix errors or improve their performance. This ensures they function correctly and efficiently, rather than for aesthetic reasons like making them colorful or fun.