Q&A – Decomposition into Algorithms (Primary 4 – 4CT.07)

Decomposition helps us design algorithms by dividing a big task into smaller parts.

• True

• False

Answer explanation

True. Decomposition is a fundamental technique in algorithm design that breaks down complex problems into manageable subproblems, making it easier to develop efficient solutions.

Which is the best example of decomposition?

• Writing one huge step: “Do homework”

• Breaking it down: “1. Open book, 2. Answer questions, 3. Check answers”

• Writing “Homework Homework Homework”

• Skipping homework altogether

Answer explanation

The best example of decomposition is breaking down a task into smaller steps, like '1. Open book, 2. Answer questions, 3. Check answers.' This approach clarifies the process, making it easier to complete the homework.

The first step when using decomposition to solve a problem is:

• Break the problem into smaller parts

• Implement the solution immediately

• Test the final solution

• Ignore the problem details

Answer explanation

The first step in decomposition is to break the problem into smaller parts. This allows for easier analysis and solution development, making it essential to understand the problem before implementing or testing any solutions.

Compare Algorithms Task: Bake a cake. • Algorithm A: Bake Cake • Algorithm B: Mix Ingredients Put in Oven Wait 30 minutes Serve Cake Which algorithm uses decomposition?

• Algorithm A

• Algorithm B

Answer explanation

Algorithm B uses decomposition by breaking down the task of baking a cake into smaller steps: mixing ingredients, putting in the oven, waiting, and serving. Algorithm A does not decompose the task.

Decomposition only works in computer programming, not in real life.

• True

• False

Answer explanation

False is correct because decomposition is a problem-solving technique applicable in both computer programming and real life. It involves breaking down complex problems into smaller, manageable parts, which is useful in various real-world scenarios.

Which set of sub-tasks correctly decomposes “Brush your teeth”?

• Run water, Put soap, Wash hands

• Pick toothbrush, Put toothpaste, Brush teeth, Rinse mouth

• Pick ball, Throw ball, Catch ball

Answer explanation

The correct decomposition of "Brush your teeth" involves specific steps: picking up the toothbrush, applying toothpaste, brushing, and rinsing. The other options do not relate to this task.

What is missing in the decomposition?

• A reactant. Example: Steps like “Add filling,” “Close bread slices,” “Cut sandwich.”

• A product

• A catalyst

• A solvent

Answer explanation

In a decomposition reaction, a reactant is necessary to break down into products. If a reactant is missing, the reaction cannot occur, making it the correct choice. A product, catalyst, or solvent are not required for the reaction to start.

How many sub-tasks are there?

• 5

• 3

• 7

• 2

Answer explanation

The question asks for the number of sub-tasks, and the correct answer is 5. This indicates that there are five distinct tasks to be completed.

Which of the following is an example of decomposition for “Cleaning your room”?

• Breaking the task into steps like picking up clothes, dusting surfaces, and vacuuming the floor.

• Cleaning the entire room in one go without any steps.

• Ignoring the mess and leaving the room as it is.

• Only focusing on one corner of the room.

Answer explanation

The correct choice breaks down "Cleaning your room" into manageable steps, making the task easier to accomplish. This method of decomposition helps organize the cleaning process effectively.

Decomposition is important when writing algorithms because:

• it breaks down complex problems into smaller, manageable parts.

• it makes algorithms run faster by default.

• it eliminates the need for testing algorithms.

• it ensures algorithms never have errors.

Answer explanation

Decomposition is crucial in algorithm design as it simplifies complex problems into smaller, manageable parts, making it easier to understand, develop, and debug algorithms.