3.2.4/5 Relational & Boolean Operators — AQA 8525

3.2.4 Relational Operators

Relational operators compare two values and return a Boolean result (True or False). They are used in conditions for IF, WHILE, and REPEAT…UNTIL.

Operator	Meaning	Example	Result
==	Equal to	5 == 5	True
!=	Not equal to	5 != 3	True
<	Less than	3 < 7	True
>	Greater than	7 > 3	True
<=	Less than or equal to	5 <= 5	True
>=	Greater than or equal to	4 >= 6	False

age ← int(INPUT("Age: "))
IF age >= 18 THEN
    OUTPUT "Adult"
ELSEIF age >= 13 THEN
    OUTPUT "Teenager"
ELSE
    OUTPUT "Child"
ENDIF

3.2.5 Boolean Operators

Boolean operators (logical operators) combine or negate Boolean values. AQA specifies AND, OR, and NOT.

Operator	Meaning	Rule
AND	Both must be True	True AND True → True; anything else → False
OR	At least one True	False OR False → False; anything else → True
NOT	Reverses Boolean	NOT True → False; NOT False → True

Truth Tables

A	B	A AND B	A OR B	NOT A
True	True	True	True	False
True	False	False	True	False
False	True	False	True	True
False	False	False	False	True

Combined Conditions

// AND — both conditions required
IF age >= 18 AND hasID == True THEN
    OUTPUT "Entry granted"
ENDIF

// OR — either condition triggers it
IF score < 0 OR score > 100 THEN
    OUTPUT "Invalid score"
ENDIF

// NOT — reverses the condition
IF NOT (username == "admin") THEN
    OUTPUT "Access denied"
ENDIF

Operator Precedence

When multiple operators appear together, the order matters: NOT → AND → OR (NOT has highest priority).

// NOT True AND False
// = (NOT True) AND False
// = False AND False = False

Use brackets to make complex conditions clear and unambiguous.

Exam tip: In truth tables, AND only gives True when BOTH inputs are True. OR gives False only when BOTH are False. These are the key patterns to memorise. De Morgan's Law: NOT(A AND B) = NOT A OR NOT B.

⚠️ Common Mistakes

Using = instead of == for comparison (= is assignment in AQA)
Confusing AND with OR — AND is stricter (both must be True)
Forgetting NOT reverses — NOT (5 > 3) = NOT True = False
Writing =! instead of != for "not equal to"

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Key points

Six relational operators: ==, !=, <, >, <=, >=
AND: both True; OR: at least one True; NOT: reversal
Truth tables for AND, OR, NOT
Combining operators in complex conditions

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✍️

Worksheet — 3.2.4 & 3.2.5

8 questions · 22 marks

Q1Complete the truth table for AND and OR: A=True, B=False[2]

✅ Mark scheme

Mark scheme

A AND B = False [1]; A OR B = True [1].

Q2Evaluate: (a) NOT True (b) NOT (5 > 3) (c) NOT (10 == 9)[3]

✅ Mark scheme

Mark scheme

(a) False [1]; (b) False — 5>3 is True, NOT True = False [1]; (c) True — 10==9 is False, NOT False = True [1].

Q3Write a condition to check if a score is a valid percentage (0 to 100 inclusive).[2]

✅ Mark scheme

Mark scheme

score >= 0 AND score <= 100 [1 for each condition, 1 for AND — 2 marks].

Q4State the result of: (5 == 5) AND (3 != 3). Show your working.[2]

✅ Mark scheme

Mark scheme

(5==5) = True; (3!=3) = False; True AND False = False [2]. One mark if result wrong but working shows correct evaluation of components.

Q5Write pseudo-code to validate that age is between 16 and 18 inclusive. Output "Eligible" or "Not eligible".[3]

✅ Mark scheme

Mark scheme

IF age >= 16 AND age <= 18 THEN [2 — both conditions with AND]; OUTPUT "Eligible" ELSE OUTPUT "Not eligible" [1]; ENDIF.

Q6What is the difference between == and = in AQA pseudo-code?[2]

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== is a comparison operator that returns True/False [1]; = (or ←) is assignment that stores a value in a variable [1].

Q7Complete the full truth table for NOT A, A AND B, and A OR B for all 4 combinations of A and B.[4]

✅ Mark scheme

Mark scheme

T,T→NOT A=F,AND=T,OR=T [1]; T,F→NOT A=F,AND=F,OR=T [1]; F,T→NOT A=T,AND=F,OR=T [1]; F,F→NOT A=T,AND=F,OR=F [1].

Q8A login system requires username = "admin" AND password = "pass123". Write an IF statement to grant or deny access.[4]

✅ Mark scheme

Mark scheme

IF username == "admin" AND password == "pass123" THEN [2]; OUTPUT "Access granted" [1]; ELSE OUTPUT "Access denied" [1]; ENDIF.

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3.2.4 Relational Operators

3.2.5 Boolean Operators

Truth Tables

Combined Conditions

Operator Precedence

Key points

Worksheet — 3.2.4 & 3.2.5

Mini Test — 3.2.4/5 Operators