Computer Science
Grade 6
20 min
5. Algorithmic Thinking: Step-by-Step Solutions
Develop algorithms as step-by-step solutions to problems, expressed in pseudocode.
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Introduction & Learning Objectives
Learning Objectives
Define 'algorithm' and 'problem decomposition' in their own words.
Break down a real-world task into a clear, sequential list of steps.
Identify the necessary inputs, the process, and the expected output for a simple problem.
Write a simple algorithm using plain English (pseudocode) to solve a problem.
Translate a simple plain-English algorithm into a sequence of text-based commands.
Evaluate a given algorithm to find missing or out-of-order steps.
Ever tried to explain how to build a LEGO set to a friend over the phone? 🤖 How do you make sure they follow the exact steps in the right order?
In this lesson, we'll learn how to think like a computer by breaking big problems into tiny, clear steps. This is called 'algorithmic t...
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Key Concepts & Vocabulary
TermDefinitionExample
AlgorithmA list of step-by-step instructions for completing a task or solving a problem.A recipe for baking cookies is an algorithm. It tells you the exact ingredients to use and the exact steps to follow.
Problem DecompositionBreaking a big, complicated problem down into smaller, more manageable parts.The problem 'Clean my room' can be decomposed into smaller tasks: 1. Make the bed. 2. Put clothes in the closet. 3. Put toys in the toy box. 4. Vacuum the floor.
SequenceThe specific order in which instructions are performed. The order matters!When getting dressed, the sequence is: 1. Put on socks. 2. Put on shoes. Doing it in the wrong order won't work.
InputThe information or materials you need to start the algorithm.For an algorithm that adds two numb...
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Core Syntax & Patterns
The 'First, Then, Next' Pattern
Always write steps in the order they must happen. Use words like 'First,' 'Then,' 'Next,' and 'Finally' to show the sequence.
Use this to make sure your instructions are clear and can't be misunderstood. Computers are very literal and will do exactly what you tell them, in the exact order you tell them.
The 'Input -> Process -> Output' Model
Before writing steps, identify: 1. What you START with (Input). 2. What you DO (Process). 3. What you END with (Output).
This helps you understand the whole problem before you start writing steps. It's like knowing your ingredients and what the final dish should look like before you start cooking.
Be Specific and Unambiguous...
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Challenging
To find a specific student's test score in a classroom, which algorithm is more efficient (faster)?
Algorithm A: Start at the first desk, ask the student's name, and continue one by one until you find the right student.
Algorithm B: Ask all students whose names start with A-M to raise their hands, then ask only those students for their name.
A.Algorithm A is more efficient because it checks every student.
B.Algorithm B is more efficient because it eliminates a large number of students in one step.
C.Both algorithms are equally efficient.
D.Neither algorithm will work.
Challenging
An algorithm finds the largest of three specific numbers: `[10, 50, 20]`. How could you use abstraction to make this algorithm work for *any* three numbers?
A.Write a separate algorithm for every possible combination of three numbers.
B.Only use the numbers `[10, 50, 20]` because they are the best.
C.Use variables like `num1`, `num2`, and `num3` as placeholders for the numbers.
D.The algorithm will automatically work for any numbers.
Challenging
An algorithm is designed to find the smallest number in a list. It works perfectly for `[3, 8, 2]` and `[10, 5, 15, 20]`. However, when given an empty list `[]`, the program crashes. This type of problem, which occurs at an extreme or unusual input, is called an:
A.Sequence error
B.Edge case
C.Input error
D.Syntax error
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