Logic statements and expressions | Computer Science | Quizalize & Oak National Academy

Starter quiz

What type of data does a logic gate process, where each value can only be True or False?

numeric

text

Boolean ✓

dates
Which logic gate does the following symbol represent?

AND

OR

NOT ✓
Which type of logic gate is used when the output is True when at least one input is True?

'OR' ✓
Match the logic gate to the description.

A AND B

⇔

Both inputs need to be True in order give the output True. ✓

A OR B

⇔

Only one input needs to be True in order to give the output True. ✓

NOT A

⇔

The input must be False to give the output True. ✓
We are building a truth table with two inputs for the expression A AND B. Put the inputs into the order most people would use to ensure all possibilities have been accounted for.

1

⇔

A = 0, B = 0

2

⇔

A = 0, B = 1

3

⇔

A = 1, B = 0

4

⇔

A = 1, B = 1
Which of these are inputs for this statement? “If it is after 9.45 PM on a weekday and it is not the school holidays, I will go to bed.”

after 9:45 PM (T) ✓

weekday (W) ✓

holidays (H) ✓

bed (B)

Exit quiz

Match the terms to the correct definitions.

Boolean

⇔

a data type that can have one of two possible values (True or False) ✓

logic expression

⇔

a combination of logical operators and variables ✓

logic circuit

⇔

a set of two or more logic gates to allow for more complex logic ✓

logic gate

⇔

an electronic component that carries out a logical operation ✓
If A = True, B = True and C = False, which of these is a correctly evaluated expression?

A AND (NOT C) = True ✓

A OR C = False

B AND C = True

NOT B = True
What is output for this expression when A = True, B = False and C = False? NOT (A OR B) AND C

'False' ✓
Label the output for this sentence: “If it is raining and not windy, I take an umbrella.”

weather (W)

raining (R)

windy (W)

umbrella (U) ✓
Write this expression another way so that the logic is still the same: X = A OR (NOT B)

'X = (NOT B) OR A' ✓
Write an expression for this sentence: “I’ll go swimming (S) if my friend (F) is coming and the pool (P) is open.”

'S = F AND P' ✓

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Lesson Details

Key learning points

A logic statement is a statement that evaluates to either True or False.
You can write a logic statement to represent an outcome where the result is dependent on Boolean variables.
Boolean logic combines multiple logic statements into an expression that is either True or False.

Common misconception

Boolean logic statements should be processed in the order they are read (from left to right).

Boolean operators have an order of precedence that affects the which operator applies to which variable. If a different order is required, brackets should be used.

Keywords

Boolean - a data type that can have one of two possible values, 0 (False) or 1 (True)
Logic statement - an expression that is either True or False
Logic expression - a combination of logical operators and variables that is either True or False