KS3 Introduction to Algorithms and Programming

1. ALGORITHMS & PROGRAMMING
FOR KS3

2. LEARNING OBJECTIVES
ALGORITHMS
• What is an algorithm?
• Designing an algorithm
• Why use flowcharts or
pseudocode?
PROGRAMMING BASICS
• Program Structure
• Sequencing
• Selection
• Iteration
• Variables

3. STARTER
SIMON SAYS

4. WHAT IS AN ALGORITHM?
• An algorithm is a set of step-by-step
instructions to complete a task or solve a
problem.
• Algorithms are NOT computer programs! They help us plan and design the
computer program code that will do the task.
• Flow charts or pseudocode are useful for
developing and visualising algorithms.

5. REAL-WORLD ALGORITHMS
TASK ALGORITHM EXAMPLE
Building flat-pack
furniture
Affix part A to part B using the
supplied Allan key.
Making a dress Cut along the grain of the fabric.
Use of Television Press ‘Guide’ to access program
listings.
Assembly
Instructions
Sewing
Pattern
TV
Operating
Manual

6. SIMPLE ALGORITHM
GETTING WASHED & DRESSED STEP 1 – GET UP
1. Get out of bed.
2. Eat breakfast.
STEP 2 – WASH
1. Go to bathroom.
2. Wash face.
STEP 3 - GET DRESSED
1. Remove pyjamas.
2. Put clothes on.
1. What are the INPUTS required to
achieve the OUTPUTS required?
2. What STEPS are needed and in
which SEQUENCE?
3. Are any DECISIONS needed?
4. Is there any REPETITION in the
process?
DO: Write an algorithm for brushing your teeth!

7. DESIGNING
ALGORITHMS
• Computers need exact instructions
on how and when to perform a task.
• We create a program that performs
exact instructions in the algorithm.
• An algorithm written using a
flowchart or pseudocode can help
us to write effective computer
programming code.
• They help to structure and
SEQUENCE (order) the instructions.
FLOWCHART & PSEUDOCODE EXAMPLE

8. WHAT IS PROGRAMMING?
A Program is CODE written in a
LANGUAGE that computers
understand.
• SEQUENCE is important so that a computer does
the task in the right order.
• SELECTION is the decision to make or question to
answer. E.g. IF, THEN, ELSE. The path through a
program changes depending on the answers.
• ITERATION is looping through (repeating) a path
until we reach our goal using FOR and WHILE
statements. Iterative programming reduces the
steps required by a program.
Code contains
STATEMENTS
(single instructions)
that tell the computer what to do.

9. EXAMPLE
Declaring variables to store our
information for use later on.
DO: Identify the variables for the ‘brushing your teeth.’
Using iteration to loop through the steps
whilst the ‘awake’ condition remains true.
Using conditional selection to determine
the path the program will take.

10. REFLECTION (PLENARY)
WHAT DID YOU LEARN?
What are your key takeaways from the lesson today?
CONFIDENCE LEVEL?
1. Understood ALL of it, very confident.
2. Understood MOST of it, fairly confident.
3. Understood SOME of it and need some support. FURTHER LEARNING…
NEXT LESSON: Datatypes, Variables, Constants and Operators.