Boolean logic: AND, OR and NOT
Every decision a computer makes eventually boils down to true or false. Three simple gates — AND, OR and NOT — are enough to build all of it.
Part of your national curriculum
- Algorithms and programming: Understand simple Boolean logic and some of its uses in circuits and programming
Lesson overview
What you'll learn in this lesson
Understand simple Boolean logic and some of its uses in circuits and programming
Key learning points
- • The three basic gates
- • Logic in programming
- • Logic in circuits
This lesson at a glance
- 25 minutes
- 17 parts to scroll through
- 3 quick checks
- Marked quiz at the end
- Gentle pace: short sittings with pauses
Words to know
Scroll down — the lesson carries on below
Watch & discover
Part 1 of 17
Watch first
Boolean logic: AND, OR and NOT
Every decision a computer makes is a gate opening.
In a nutshell
Understand simple Boolean logic and some of its uses in circuits and programming
Learning cycle
Part 2 of 17
Learning cycle 1 of 2
Part 1 · The three basic gates
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 3 of 17
Learn
The three basic gates
AND is only true when both inputs are true. OR is true when at least one input is true. NOT simply flips a value: true becomes false. A truth table for AND with inputs A and B: 0&0=0, 0&1=0, 1&0=0, 1&1=1 — only the last row is true.
Reset break
Part 4 of 17
Pause
That's sitting 1 of 4 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Explore the idea
Part 5 of 17
Learn
Logic in programming
In code, `if raining AND cold: wear coat` only fires when both conditions hold. `if raining OR windy: take umbrella` fires if either is true. Programmers combine these to build precise conditions, such as `age >= 13 AND age <= 18` to spot teenagers.
Quick check
Part 6 of 17
Quick check
Part 7 of 17
Reset break
Part 8 of 17
Pause
That's sitting 2 of 4 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Learning cycle
Part 9 of 17
Learning cycle 2 of 2
Part 2 · Logic in circuits
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 10 of 17
Learn
Logic in circuits
Physical logic gates are tiny electronic circuits inside a chip. An AND gate's output wire only carries current when both input wires do. Millions of these gates wired together let a processor add numbers, compare values and make decisions.
Quick check
Part 11 of 17
Reset break
Part 12 of 17
Pause
That's sitting 3 of 4 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Challenge round
Part 13 of 17
Game · Sort it
Which of these are true?
Drag each card into the right column. Tap a card first if dragging is fiddly.
True
Not true
Challenge round
Part 14 of 17
Game · Fill the gaps
Finish the sentences
Choose the word that belongs in each gap.
Physical logic gates are tiny electronic ____ inside a chip.
Challenge round
Part 15 of 17
Game · Recall cards
What does an AND gate output when both inputs are true?
Card 1 of 3
Mastery quiz
Part 16 of 17
Marked quiz
End of lesson quiz: Boolean logic: AND, OR and NOT
3 questions, marked with the reasoning shown. No timer.
1. What does an AND gate output when both inputs are true?
2. Which condition matches 'if raining OR windy: take umbrella'?
3. What does a NOT gate do to a true input?
Lesson round-up
Part 17 of 17
Lesson round-up
Ready when you are
Quiz score
Not sat
Games
Not played
Points this lesson
0
Best run
0 in a row
Luna: 0 out of 3 on the practice checks. Only if you feel up to it — one more?
Ask LunaPart 1 of 17 · Watch & discover
How this is going
- Not looked at yet
Understand simple Boolean logic and some of its uses in circuits and programming