The person at the cinema door

A worker at the cinema door checks you. Are you 15 or older? Do you have a ticket? You can go in only if both answers are yes.

Each question has a yes or no answer: True or False. A program asks the same questions with two kinds of operator. An operator is a symbol or word that does something to values.

Key words

Word	What it means	Example
Relational operator	An operator that compares two values and gives True or False.	age >= 15
Boolean	A value that is True or False.	True
Boolean operator	An operator that joins True and False values: and, or, not.	a and b
Operator	A symbol or word that does something to values.	>
Truth table	A table that shows the result of a Boolean operator for every case.	True and False is False
Condition	A question that gives True or False.	score > 10

The cells students fill in are left blank in this preview.

Try it: compare

Code: python

age = 16

print(age == 16)
print(age < 16)
print(age >= 16)
print(age != 20)

# Each line asks a question. The answer is True or False.
# Change age to 15 and run again.

The six relational operators

Operator	Means	Example	Result when age is 16
`==`	Is equal to	`age == 16`	True
`!=`	Is not equal to	`age != 16`	False
`<`	Is less than	`age < 16`	False
`>`	Is greater than	`age > 16`	False
`<=`	Is less than or equal to	`age <= 16`	True
`>=`	Is greater than or equal to	`age >= 16`	True

The cells students fill in are left blank in this preview.

One equals or two?

data-callouts.warning.label

One = puts a value into a name. Two == asks a question: are these equal? Writing if age = 16 is a mistake. Write if age == 16.

True or False?

Have a go

True or False?

4 questions

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Join questions with and, or, not

and needs both sides to be True. or needs at least one side to be True. not turns True into False and False into True.

A truth table shows every case.

Truth table for and, or

A	B	A and B	A or B
True	True	True	True
True	False	False	True
False	True	False	True
False	False	False	False

The cells students fill in are left blank in this preview.

Truth table for not

A	not A
True	False
False	True

The cells students fill in are left blank in this preview.

Comparing and combining with and, or, not

The person at the cinema door

Key words

Try it: compare

The six relational operators

One equals or two?

True or False?

True or False?

Join questions with and, or, not

Truth table for and, or

Truth table for not

The lesson goes on