Conditional logic (if-then decisions) in Intro to Computing - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a number is positive.

Intro to Computing

if number [1] 0:
    print("Positive number")

Drag options to blanks, or click blank then click option'

A<

B>

C==

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' will check for negative numbers.

Using '==' checks only if the number is exactly zero.

The condition number > 0 checks if the number is greater than zero, meaning it is positive.

2fill in blank

medium

Complete the code to print "Even" if the number is divisible by 2.

Intro to Computing

if number [1] 2 == 0:
    print("Even")

Drag options to blanks, or click blank then click option'

A//

B+

C%

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' or '*' instead of '%' will not check divisibility.

Using '//' gives the quotient, not the remainder.

The modulus operator % gives the remainder of division. If number % 2 == 0, the number is even.

3fill in blank

hard

Fix the error in the code to check if a number is negative.

Intro to Computing

if number [1] 0:
    print("Negative number")

Drag options to blanks, or click blank then click option'

A>=

B>

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' checks for positive numbers instead.

Using '==' checks only if the number is zero.

The condition number < 0 correctly checks if the number is less than zero, meaning it is negative.

4fill in blank

hard

Fill in the blank to print "Adult" if age is 18 or older.

Intro to Computing

if age [1] 18:
    print("Adult")

Drag options to blanks, or click blank then click option'

A>=

B<

Cand

Dor

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>=' will check the wrong condition.

Using 'and' or 'or' incorrectly can cause logic errors.

The condition age >= 18 checks if the age is 18 or older.

5fill in blank

hard

Fill all three blanks to create a dictionary of words and their lengths for words longer than 3 characters.

Intro to Computing

lengths = [1]: [2] for [3] in words if len([3]) > 3

Drag options to blanks, or click blank then click option'

Aword

Blen(word)

Dw

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

Putting the length function in the wrong place.

This dictionary comprehension uses word as the variable to iterate over words. The key is word itself, and the value is len(word), but only for words longer than 3 characters.

Practice

1.

What does an if statement do in a program?

easy

A. It stores data in a list.

B. It repeats code multiple times.

C. It checks a condition and runs code only if the condition is true.

D. It creates a new variable.

Solution

1. Step 1: Understand the purpose of if

   An if statement asks a question that can be true or false.

2. Step 2: Identify what happens when the condition is true

   If the condition is true, the program runs the code inside the if block; otherwise, it skips it.

3. Final Answer:

   It checks a condition and runs code only if the condition is true. -> Option C

4. Quick Check:

   if = condition check [OK]

Hint: Remember: if means 'only if true' run code [OK]

Common Mistakes:

• Thinking if repeats code like a loop
• Confusing if with data storage
• Believing if creates variables

2.

Which of the following is the correct syntax for an if statement in Python?

___ x > 10:
    print("x is greater than 10")

easy

A. else

B. for

C. while

D. if

Solution

1. Step 1: Identify the keyword for condition checking

   Python uses if to start a condition check.

2. Step 2: Match the syntax with the code block

   The colon : after the condition is required to start the indented block.

3. Final Answer:

   if -> Option D

4. Quick Check:

   Python if syntax = if [OK]

Hint: If checking condition, start with 'if' keyword [OK]

Common Mistakes:

• Using 'for' or 'while' instead of 'if'
• Forgetting the colon after the condition
• Using 'else' without an 'if'

3.

What will be printed by this Python code?

age = 20
if age >= 18:
    print("Adult")
else:
    print("Child")

medium

A. Adult

B. No output

C. Child

D. Error

Solution

1. Step 1: Check the condition age >= 18

   Variable age is 20, which is greater than or equal to 18, so condition is true.

2. Step 2: Determine which block runs

   Since condition is true, the print("Adult") line runs, printing "Adult".

3. Final Answer:

   Adult -> Option A

4. Quick Check:

   20 >= 18 = Adult [OK]

Hint: Check if condition is true to pick printed output [OK]

Common Mistakes:

• Choosing 'Child' without checking condition
• Thinking no output if condition true
• Assuming syntax error

4.

Find the error in this code snippet:

if score > 50
    print("Pass")
else:
    print("Fail")

medium

A. Wrong indentation of print statements

B. Missing colon after if condition

C. Using else without if

D. Incorrect comparison operator

Solution

1. Step 1: Check syntax of if statement

   Python requires a colon : at the end of the if condition line.

2. Step 2: Identify the missing colon

   The line if score > 50 is missing the colon, causing a syntax error.

3. Final Answer:

   Missing colon after if condition -> Option B

4. Quick Check:

   Colon needed after if condition [OK]

Hint: Look for missing colon after if condition line [OK]

Common Mistakes:

• Ignoring missing colon error
• Thinking indentation is wrong here
• Confusing else usage

5.

You want to write a program that prints "Good morning" if the hour is less than 12, and "Good afternoon" otherwise. Which code correctly implements this?

hour = 10
___ hour < 12:
    print("Good morning")
else:
    print("Good afternoon")

hard

A. if

B. else if

C. elif

D. while

Solution

1. Step 1: Choose the correct keyword for the first condition

   The first condition must start with if to check if hour < 12.

2. Step 2: Use else for the alternative

   The else block runs if the if condition is false, printing "Good afternoon".

3. Final Answer:

   if -> Option A

4. Quick Check:

   Use if for first condition, else for alternative [OK]

Hint: Start conditions with if, alternatives with else [OK]

Common Mistakes:

• Using 'else if' instead of 'if' in Python
• Using 'elif' without a preceding if
• Using 'while' instead of if for decisions