Algorithms

1
Algorithms

• Y10 Introduction

2
WHAT IS AN ALGORITHM?

• It is a set of instructions of how to carry out a
  process. An algorithm lists the steps that must
  be followed to complete the process and to reach
  the solution

3
Examples of algorithms

• A knitting pattern
• A set of instructions telling you how to put a
  kit together (eg. an IKEA kitchen unit)
• A recipe in a cook book
• An algorithm can be represented diagrammatically
  in the form of a flow chart.

4
A flow chart

• A flowchart consists of a sequence of
  instructions linked together by arrows to show
  the order in which the instructions must be
  carried out.
• It provides detailed steps.
• Each instruction is put into a box. The boxes are
  different shapes depending upon what the
  instruction is.

5
Process shapes
Remember not to create the flow chart in
WORD Instead do this in POWER POINT and
change File Page Layout to PORTRAIT Autoshapes
has the shapes you need to use
Input or output
START / END
Query / question
Human process i.e. you doing something!
No
Yes
Printed output
Save to file
6
More shapes

• You can also use the following shapes
• Predefined process
• Used for a sequence of instructions which is
  defined somewhere else (eg. in a subroutine)
• Connector
• to link with a different page or another part
  of the program
• (Note all these shapes can be found under
  AutoShapes
• if you click the Drawing icon on your tool bar)

Predefined process
7
TASK 1 MAKING A CUP OF TEA!

• The following list represents the steps needed in
  order to make a cup of tea. Put the list in the
  right order and produce an algorithm in
  POWERPOINT showing the processes and decisions
  you need to make.

• Take tea bag out of cup
• Boil the water
• Put tea bag in cup
• Add milk?
• Pour boiling water in cup
• Fill kettle
• Stir
• Ready
• Add sugar ?
• Fetch cup

Answers follow
8
The answers
START
Fill kettle

• Fill kettle
• Boil the water
• Fetch cup
• Put tea bag in cup
• Pour boiling water in cup
• Take tea bag out of cup
• Add sugar ?
• Stir
• Add milk?
• Stir
• Ready

Boil the water
Fetch cup
Put tea bag in cup
Pour boiling water in cup
Take tea bag out of cup
Add sugar ?
N
Stir in sugar
Add milk?
N
Now add the shapes
Pour in milk
Ready
9
Skills in Powerpoint to create your algorithm.
To change this to .
To tidy up the whole column select all (drag
around all shapes) Go to DRAW Select ALIGN or
DISTRIBUTE
10
START
Fill kettle
Boil the water
To this but take care as it can mess up the
side sections!
Fetch cup
Put tea bag in cup
Pour boiling water in cup
Take tea bag out of cup
Add sugar ?
N
Stir in sugar
Add milk?
N
Ready
Pour in milk
11
TASK 2A PREDEFINED PROCESS

• In order to carry out no. 8 in the list above,
  you will need to instruct the user how to fill a
  kettle.
• (a) Produce a set of instructions called Filling
  a kettle and then
• (b) update your algorithm for task 1 to include
  this predefined process.

12
TASK 3MAKING A CUP OF COFFEE!

• How would your algorithm change for making a cup
  of coffee instead of tea? Amend your algorithm in
  Task 2 (b) in order to produce a new diagram.

13
Now try to create one on a PC

• This should always be done in POWERPOINT..
• NEVER, EVER, EVER in WORD!