Computer Science
Grade 5
20 min
Reading Error Messages
Reading Error Messages
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1
Introduction & Learning Objectives
Learning Objectives
Identify the three main parts of an error message: the type, the description, and the line number.
Differentiate between a Syntax Error and a NameError.
Use the line number from an error message to locate the problem in their code.
Correct a simple syntax error, like a missing colon, based on an error message.
Correct a misspelled variable name based on a NameError message.
Explain that error messages are helpful tools, not signs of failure.
Have you ever built something with blocks, and the whole tower came crashing down? 💥 Error messages are like clues that tell you which block was in the wrong spot!
In this lesson, you will become a code detective! We will learn how to read the secret clues hidden in error messages. Understanding these messages is a...
2
Key Concepts & Vocabulary
TermDefinitionExample
Error MessageA message from the computer that tells you it found a problem in your code and couldn't run it.A message that says 'SyntaxError: invalid syntax' is an error message.
BugA mistake or problem in a computer program that stops it from working correctly.If your character in a game can walk through walls, that's a bug.
DebuggingThe process of finding and fixing bugs in your code. Reading error messages is the first step of debugging.You see an error, find the line with the mistake, and fix it. You are debugging!
Syntax ErrorAn error caused by breaking the grammar rules of the programming language, like a typo or a missing symbol.Forgetting the colon ':' at the end of a loop statement like 'for i in range(5)'.
NameErrorAn...
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Core Syntax & Patterns
The Three Clues Rule
Look for 1) The Line Number, 2) The Error Type, and 3) The Description.
Every error message gives you clues. First, find the line number to know where to look. Second, identify the type (like SyntaxError or NameError) to know what kind of problem it is. Third, read the description for more details.
Read from the Bottom Up
The most important information in an error message is usually on the last line.
Error messages can sometimes be long and confusing. Start by reading the very last line. It gives you the most direct summary of the problem.
Check Above and Below
The mistake might be on the line *before* the one in the error message.
Sometimes the computer doesn't notice a mistake until it gets to the next line. If the line number in the error...
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Challenging
A program converts numbers 1-10 to binary strings and stores them in a list. It crashes with an `IndexError: list assignment index out of range` on line 42 when the number is 8. The binary for 7 is '111' and for 8 is '1000'. What is the most likely cause of this error?
A.The computer's memory is full.
B.The list was created with a fixed size that is too small for a 4-digit binary number.
C.The number 8 cannot be represented in binary.
D.`for` loop cannot handle the number 8.
Challenging
On line 10, you misspell a variable name: `player_scrore = 0`. On line 50, you try to use it correctly: `if player_score > 10:`. The program crashes with a `NameError: name 'player_score' is not defined` on line 50. What is the ROOT CAUSE of the error?
A.The variable was misspelled on line 10 where it was created.
B.The `if` statement on line 50 is written incorrectly.
C.The variable `player_score` was never used after line 10.
D.The number 10 is an invalid value for a score.
Challenging
A program with a `while` loop that adds items to a list runs for a minute and then crashes with a `MemoryError`. What is the most probable explanation?
A.The computer's hard drive is full.
B.The list contained too many items with the letter 'M'.
C.The loop is an infinite loop that kept adding items to the list until the computer ran out of RAM.
D.The program tried to access a secret part of the computer's memory.
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