Making Decisions | Hallam IT Basics

1. One equals stores, two equals compares

This is the number-one beginner mix-up, so get it straight first:

= stores. age = 13 puts the value 13 into the variable age.
== compares. age == 13 asks a question, “is age equal to 13?”, and answers True or False.

age = 13        # change this with the control below
print(age == 13)  # is age equal to 13?
print(age == 10)  # is age equal to 10?

Read it out loud. = is “becomes”. == is “is equal to?”. They are not the same thing.

2. Comparison operators and Booleans

Every comparison gives back a Boolean, either True or False.

Operator	Means	Example	Result
`==`	is equal to	`5 == 5`	`True`
`!=`	is not equal to	`3 != 3`	`False`
`>`	is greater than	`9 > 4`	`True`
`<`	is less than	`9 < 4`	`False`
`>=`	greater than or equal	`13 >= 13`	`True`
`<=`	less than or equal	`12 <= 11`	`False`

Try reading each of these and deciding the answer before you check: is 5 == 5? is 3 != 3? is 9 > 4?

3. The if statement

An if runs the indented code only when its condition is True. Two things matter: the colon at the end of the if line, and the indentation (4 spaces) that marks the body.

age = 15
if age >= 13:
    print("You are old enough.")

If the condition is False, the indented line simply does not run, so nothing is printed.

Seen this shape before? It's the one the exam asks for as pseudocode: IF age >= 13 THEN … ELSE … ENDIF. Python is the same plan with a colon and indentation in place of THEN and ENDIF.

4. if / else

else covers everything the if did not. Exactly one of the two blocks runs.

score = int(input("What did you score on the test? "))

if score >= 50:
    print("You passed! Well done.")
else:
    print("Not quite, have another go.")

Indentation marks the blocks. Python uses the spaces to know which lines belong to the if and which belong to the else.

5. Worked example: secret-word game

This pulls Lesson 1 (input()) and today’s lesson (if / else with ==) together.

secret = "python"
guess = input("Guess the secret word: ")

if guess == secret:
    print("Correct! You got it.")
else:
    print("Nope, try again.")

Notice we compare with == (a question), never = (which would try to store).

6. Quick check Part 1 of 2

Six quick questions. This is half of completing the module. The coding task below is the other half.

What does == do?

In age = 13, what does the single = do?

Is this condition True or False? 5 == 5

Is this condition True or False? 3 != 3

In an if / else, when does the else block run?

What must go at the end of an if line in Python?

7. Coding task: Old enough to sign up? Part 2 of 2

Write a real program below and press Check. Our app is for ages 13 and over. Read an age, then use if / else to either let them in or turn them away. Passing this is the other half of completing the module.

solution.py

Output

Ctrl+Enter runs your code · Tab inserts 4 spaces · Python loads the first time you press Run or Check (5-10 seconds), then it’s instant.

How the module is marked: the quick check is worth 50% and this coding task is worth 50%. Do both to reach 100%. Your teacher can see your score on the progress page.

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