Computer Science
Grade 2
20 min
The Wrong Color
Identifying the incorrectly colored object in a sequence.
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1
Introduction & Learning Objectives
Learning Objectives
Identify a 'bug' when a program produces an unexpected color.
Define the term 'debugging' as finding and fixing mistakes.
Step through code blocks one by one to find an error.
Predict the outcome of a simple color pattern program.
Correct a single incorrect code block to fix a color pattern.
Explain why checking code in order is important for finding bugs.
Oh no! 🙀 Your robot was supposed to paint a red and blue fence, but it used green! How can we fix it?
We will be detectives today! 🕵️♀️ We will learn how to find mistakes, called 'bugs', in our code. Finding and fixing bugs is called debugging.
Real-World Applications
Fixing a toy that isn't working right.
Finding the wrong ingredient in a recipe.
Figuring o...
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Key Concepts & Vocabulary
TermDefinitionExample
Bug 🐛A bug is a mistake in the code. It makes the computer do the wrong thing.You want a cat to say 'Meow', but it says 'Woof'. The 'Woof' is a bug.
Debugging 🕵️Debugging is finding and fixing bugs. It is like being a code detective.You find the 'Woof' block and change it to a 'Meow' block. That's debugging!
Code Block 🧱A code block is one instruction for the computer. It tells the computer to do one thing.A block that says 'Paint Red' or 'Move Forward'.
Sequence ➡️A sequence is the order of the code blocks. The computer follows them one by one.First, 'Paint Red'. Second, 'Paint Blue'. Third, 'Paint Red'.
Pattern 🎨A pattern is something that repeats in a certai...
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Core Syntax & Patterns
The Detective's First Step
Run the code and watch carefully. 👀
First, see what the bug does. Compare what you see with what you wanted.
One Clue at a Time
Check each code block in order. 1️⃣ 2️⃣ 3️⃣
Go through your code from top to bottom. Don't skip any blocks!
Find the Mismatch
Find the block where the code does the wrong thing. ❌
When you find the step that is wrong, you have found the bug!
4 more steps in this tutorial
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Challenging
Your friend wants a purple flower. They used a special [Mix Colors] block. Their code is: [Set Primary Color to Yellow], [Set Secondary Color to Blue], [Mix Colors], [Draw Flower]. Why isn't the flower purple?
A.The [Draw Flower] block should be before the [Mix Colors] block
B.Yellow and blue do not make purple
C.The code is missing a [Repeat] block
D.The computer does not know the color purple
Challenging
Goal: Draw a pattern of Red-Blue-Red-Blue squares. Code: [Repeat 2 times] { [Set Color to Red], [Draw Square], [Set Color to Blue] }. What does this code actually draw?
A.red square and a blue square
B.red square and then nothing
C.Two blue squares
D.purple square
Challenging
A caterpillar should be alternating green and yellow. The buggy code is: [Set Color to Green], [Repeat 4 times] { [Draw Circle] }. What is the BEST way to fix this?
A.Put [Set Color to Green] and [Set Color to Yellow] blocks inside the loop
B.Take the code out of the loop and write 8 blocks
C.Change [Set Color to Green] to [Set Color to Yellow]
D.Change the repeat number from 4 to 2
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