Creating an XOR function
Lesson details
Learning outcome
I can write a function that replicates the output of an XOR gate.
Key learning points
- A logic gate is a fundamental component of a digital circuit.
- A truth table shows all possible combinations of inputs and the output that a circuit will produce.
- An XOR logic gate is True when either input is True, but not both.
- Unlike AND, OR and NOT, Python does not have a built-in operator for XOR.
Keywords
Logic gate - an electronic component that carries out a logical operation
Truth table - a table showing the outputs for all possible combinations of inputs to a logic gate or logic circuit
XOR - a Boolean operation that outputs True if either, but not both, of the input values are True
Common misconception
Python has a built-in XOR operator in the same way that it has AND, OR and NOT.
Unlike AND, OR and NOT, Python does not have a built-in operator for XOR and instead must be designed as part of and program that uses it.
Teacher tip
XOR is like a light that can be changed by two different light switches. Explore how turning on one switch turns the light on, but when both are on it turns off.
Equipment
Pupils will need access to a device that can edit and run Python programs. Examples in this lesson use the RPF Code Editor https://oak.link/python-editor
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What will be the output when this program is run?
1234567num1 = 5
num2 = 10
if num1 < 6 and num2 > 8:
print("That is True")
else:
print("That is False")Code colour
Q2.What will be the output when this program is run?
1234567num1 = 5
num2 = 10
if num1 == 5 or num2 > 11:
print("That is True")
else:
print("That is False")Code colour
Q3.Match the definition to the keyword.
the section of a program where a variable can be accessed and modified
only defined and visible for use in specific parts of a program
accessible from all parts of a program
Q4.What will be the output when this program is run?
123456def divide(a, b):
answer = a / b
return answer
divide(8, 2)
print(answer)Code colour
Q5.Which of the following are reasons why global variables should be avoided?
Q6. passing is the process of passing data into a subroutine and can be used as an alternative to global variables.
Assessment exit quiz
4 Questions
Q1.Which of the following are built-in operators in Python?
Q2.What will this code output?
1234one = 4 == 4
two = 2 != 2
print(xor_function(one, two))Code colour
Q3.What will this code output?
1234one = 4*2 == 32/4
two = 2 == 2
print(xor_function(one, two))Code colour
Q4.Which logic gate symbol is used to represent XOR?
To help you plan your 10 computer science lesson on: Creating an XOR function, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 computer science lesson on: Creating an XOR function, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 computer science lessons from the Programming: subroutines unit, dive into the full secondary computer science curriculum, or learn more about lesson planning.