Variables and data storage in Intro to Computing - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to store the number 10 in a variable named score.

Intro to Computing

score = [1]

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

A10

B"10"

Cscore

Dten

Attempts:

3 left

💡 Hint

Common Mistakes

Putting the number 10 inside quotes, which makes it a string.

Using the variable name on the right side instead of a value.

The variable score is assigned the number 10 without quotes because numbers are stored as numeric values, not strings.

2fill in blank

medium

Complete the code to store the text 'hello' in a variable named greeting.

Intro to Computing

greeting = [1]

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

Ahello

B'greeting'

C"hello"

Dgreeting

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around the text.

Using the variable name instead of the text.

Text values (strings) must be enclosed in quotes. Here, double quotes are used around hello.

3fill in blank

hard

Fix the error in the code to correctly store the value 5 in variable count.

Intro to Computing

count = [1]

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

A5

Bfive

Ccount

D"5"

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around the number.

Using a word instead of a number.

The value 5 should be stored as a number without quotes. Using quotes makes it a string, and using words like 'five' is invalid.

4fill in blank

hard

Fill both blanks to create a variable age and assign it the value 30.

Intro to Computing

[1] = [2]

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

Aage

B30

Cage

D"30"

Attempts:

3 left

💡 Hint

Common Mistakes

Adding spaces or quotes around the variable name.

Putting the number 30 in quotes, making it a string.

The variable name age should be on the left side without quotes or spaces, and the number 30 on the right side as a numeric value.

5fill in blank

hard

Fill all three blanks to create a variable name and assign it the text 'Alice'.

Intro to Computing

[1] = [2] + [3]

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

Aname

B"A"

C"lice"

DAlice

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around text parts.

Using the full name without quotes or concatenation.

The variable name is assigned by joining two strings: "A" and "lice". This shows how text can be combined to form 'Alice'.

Practice

1. What is a variable in computing?
Example: Think of a variable as a labeled box where you can store something.

easy

A. A container that holds data values

B. A type of computer hardware

C. A program that runs automatically

D. A tool to clean computer screens

Solution

1. Step 1: Understand the concept of variables

   A variable is like a labeled box where you can store data such as numbers or words.

2. Step 2: Match the description to the options

   A container that holds data values describes a container holding data values, which matches the idea of a variable.

3. Final Answer:

   A container that holds data values -> Option A

4. Quick Check:

   Variable = labeled box for data [OK]

Hint: Variables store data like boxes hold items [OK]

Common Mistakes:

• Confusing variables with hardware
• Thinking variables run programs
• Mixing variables with tools or devices

2. Which of the following is the correct way to create a variable named age and store the number 25 in it?

easy

A. int age = 25

B. age = 25

C. age := 25

D. 25 = age

Solution

1. Step 1: Identify the correct assignment syntax

   In many programming languages, assigning a value to a variable uses the format: variable = value.

2. Step 2: Check each option

   age = 25 uses age = 25, which is the standard way to assign 25 to variable age.

3. Final Answer:

   age = 25 -> Option B

4. Quick Check:

   Variable assignment uses = sign [OK]

Hint: Variable name on left, value on right with = [OK]

Common Mistakes:

• Putting value before variable
• Using wrong assignment symbols
• Confusing variable declaration syntax

3. What will be the value of total after running this code?

price = 10
quantity = 3
total = price * quantity

medium

A. 30

B. 13

C. 103

D. Error

Solution

1. Step 1: Understand the variables and operation

   price is 10, quantity is 3, and total is assigned price multiplied by quantity.

2. Step 2: Calculate the multiplication

   10 * 3 = 30, so total will be 30.

3. Final Answer:

   30 -> Option A

4. Quick Check:

   10 x 3 = 30 [OK]

Hint: Multiply values stored in variables [OK]

Common Mistakes:

• Adding instead of multiplying
• Concatenating numbers as strings
• Expecting syntax error

4. Identify the error in this code snippet:

number = 5
Number = 10
print(number + Number)

medium

A. Missing semicolon at the end of lines

B. Cannot add two variables together

C. Variables must start with a capital letter

D. Variable names are case-sensitive, so both are different variables

Solution

1. Step 1: Check variable names and case sensitivity

   Variables number and Number differ by case and are treated as two separate variables.

2. Step 2: Understand the addition operation

   Adding number (5) and Number (10) is valid and results in 15.

3. Final Answer:

   Variable names are case-sensitive, so both are different variables -> Option D

4. Quick Check:

   Case matters in variable names [OK]

Hint: Remember variable names are case-sensitive [OK]

Common Mistakes:

• Assuming variables with different cases are same
• Expecting syntax error for missing semicolons
• Thinking variables can't be added

5. You want to store the names and ages of three friends in variables. Which approach correctly uses variables to store this data for easy access later?

hard

A. name1 = 'Anna'; age1 = 20; name2 = 'Ben'; age2 = 22; name3 = 'Cara'; age3 = 19

B. friends = ['Anna', 20, 'Ben', 22, 'Cara', 19]

C. friends = {'Anna': 20, 'Ben': 22, 'Cara': 19}

D. names = ['Anna', 'Ben', 'Cara']; ages = [20, 22, 19]

Solution

1. Step 1: Understand the need for easy access to names and ages

   We want to link each friend's name to their age clearly and accessibly.

2. Step 2: Evaluate each option's data structure

   friends = {'Anna': 20, 'Ben': 22, 'Cara': 19} uses a dictionary (key-value pairs) where names are keys and ages are values, making access easy and clear.

3. Final Answer:

   friends = {'Anna': 20, 'Ben': 22, 'Cara': 19} -> Option C

4. Quick Check:

   Use key-value pairs for related data [OK]

Hint: Use key-value pairs to link related data [OK]

Common Mistakes:

• Using separate variables for each item
• Mixing names and ages in one list without structure
• Using parallel lists which are harder to manage