Using Selection in Programs
Using Selection in Programs
Lesduur is: 50 minOnderdelen in deze les
Using Selection in Programs
Deze slide heeft geen instructies
Learning goal
I can use if and if-else to make a program choose what to do.
Deze slide heeft geen instructies
What words come to mind when you hear coding decisions?
Use this to activate prior knowledge. Accept ideas such as choice, rule, true, false, button, answer, game or traffic lights, then link them to selection.
Lesson introduction
This KS2 computing lesson explores Using Selection in Programs. Pupils use if and if-else decisions to make programs respond differently to conditions and user input. It is suitable for classroom teaching, independent practice or a clear recap of the topic.
Deze slide heeft geen instructies
What does selection mean?
Selection means a program chooses between actions.
It checks a condition such as true or false and then decides what to do next.
Link to everyday choices pupils know, such as 'if it is raining, take a coat'. Keep the focus on computing: the computer follows rules we give it.
Programs do not always do the same thing
A program can respond to:
what a user types
which button is pressed
a score or number
whether something is true or false
Selection helps the program give the right response.
Deze slide heeft geen instructies
Selection in real life
We use rules like these every day:
if the light is green, go
if the light is red, stop
if it is cold, wear a jumper
Programs use similar decision rules.
This slide activates prior knowledge without making it an interactive task. Emphasise that computers do not guess; they follow exact conditions.
A condition checks something
A condition is a check.
Examples:
score is greater than 9
answer equals 12
button is pressed
password is correct
The result is either true or false.
Pupils may say 'right or wrong'. Accept this, then connect it to true and false in code.
What does selection let a program do?
Choose an action
Draw a picture
Charge a battery
Print a keyboard
Checks the core idea from slides 3 to 6: selection means choosing between actions after checking a condition.
Complete the selection words
A program uses selection to choose between actions. It checks a condition and the result is either true or false.
Support lower-attaining pupils by revisiting the everyday examples from traffic lights and getting dressed for the weather.
Using if
An if statement tells a program:
If a condition is true, do something.
If the condition is false, the program skips that action and carries on.
Deze slide heeft geen instructies
Example of if
```text
if score > 9
say "You win!"
```
The message only appears when the score is more than 9.
You do not need to teach a specific programming language here. Treat the code as simple pseudocode pupils can read.
Using if-else
An if-else statement gives two possible actions.
if the condition is true, one action happens
else a different action happens
This helps a program respond in more than one way.
Deze slide heeft geen instructies
Example of if-else
```text
if answer = 10
say "Correct"
else
say "Try again"
```
The program always gives one of the two messages.
Highlight the contrast with plain if: with if-else, something happens whether the condition is true or false.
What happens with only an if statement when the check is false?
It repeats the check
It shows both actions
It skips the action
It stops the program
Tests the contrast taught on slides 7 and 8: plain if only runs when true; otherwise the action is skipped.
Why is if-else useful?
It stores the input
It gives two actions
It draws the screen
It changes the keyboard
This checks understanding of the key difference between if and if-else from slides 9 and 10.
How is if-else different from if?
Expected elements: an if statement has one action only when the condition is true; an if-else gives one action when true and a different action when false. Encourage pupils to use a simple example such as score, answer or button pressed.
User input can change the result
When a user clicks, types or chooses something, the program can check it.
That input becomes part of the condition, so the output can change.
Use familiar examples such as a quiz, a login, or choosing an answer in a game.
Selection in a quiz game
A quiz might work like this:
user answer → program checks answer →
correct answer gives one message
wrong answer gives a different message
Selection makes the quiz feel responsive.
Deze slide heeft geen instructies
Selection in a simple game
A game can use rules such as:
if lives = 0, show Game over
if score > 99, show Level up
else keep the game going
These decisions help control what happens next.
Deze slide heeft geen instructies
In a quiz, what can the program check first?
The table colour
The user answer
The classroom door
The pencil case
Anchored to slides 11 to 13 about user input in quizzes and games.
Fill the quiz rule
In a quiz, the user types an answer. The program checks the input and gives an output that can change if the answer is correct or wrong.
This acts as an application task in familiar context. Pupils apply vocabulary from the content to the quiz example.
Which example of selection do you understand best?
Quiz answer
Game score
Button press
Password check
Deze slide heeft geen instructies
Why selection matters
Without selection, every program would do the same thing every time.
Selection helps programs:
react to input
check rules
give different outputs
feel useful and interactive
Deze slide heeft geen instructies
Common mistakes to avoid
Watch out for these errors:
the condition is unclear
the wrong action is inside if
else is missing when two outcomes are needed
the program checks the wrong input
Good selection needs clear rules.
If useful, model a faulty rule and ask what would happen. Keep explanation brief because interactions are handled later.
Planning a selection rule
Before coding, think about:
What needs to be checked?
What makes the condition true?
What should happen if it is true?
What should happen if it is false?
This helps you design the program clearly.
This supports later application work the teacher may run, while staying content-focused in this pass.
From rule to code
Everyday rule:
If the password is correct, open the page. Else, show an error.
Program rule:
check the input
compare it with the correct password
choose the matching action
Stress that selection is about turning a rule into a precise computer instruction.
When do you need else most?
When two outcomes are needed
When no input is checked
When the screen is blank
When the code is colourful
Based on slides 14 to 17 and the mistakes slide. The misconception is thinking else is always needed, rather than when there are two outcomes.
Complete the planning steps
Before coding, plan the condition first. Decide what makes it true, then choose the action for true and the action for false. This turns a rule into clear code.
Useful for differentiation: invite confident pupils to invent their own rule after completing the blanks, while others can rehearse the four planning questions aloud.
What rule would you plan before coding?
Expected elements: identify what is checked, what makes it true, what happens if true, and what happens if false. Accept everyday or computing examples, especially password, score or answer examples from slides 16 and 17.
What is one thing you learned today?
Reflection only. Invite brief answers about if, if-else, conditions, input or outputs.
What helped you understand selection best?
Reflection only. This helps the teacher see which explanation, example or activity supported understanding best.
How confident do you feel about using if and if-else now?
Deze slide heeft geen instructies
Glossary
selection - when a program chooses between actions
condition - a check that is either true or false
if - a command that runs an action when a condition is true
if-else - a command with one action for true and another for false
user input - information a person gives to a program
output - what a program shows, says or does
pseudocode - simple code-like writing used to plan a program
Deze slide heeft geen instructies
