Lesson Notes By Weeks and Term - Senior Secondary 2

Algorithms and flowcharts II

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Term: 2nd Term

Week: 8

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 2 periods each

Date:       

Subject:      Data Processing

Topic:-       Algorithms and Flowcharts II

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

  1. Define a flowchart;
  2. State the functions of a flowchart;
  3. State the characteristics of a flowchart;
  4. Identify flowchart symbols and state their meaning and uses;
  5. Write an algorithm and design the flowcharts for solving problems

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, pictures, Data Processing for senior Secondary Education by Hiit Plc, WAPB Computer Studies for Senior Secondary I by Adekunle et al, On-line Materials.

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S ACTIVITY

STEP 1

INTRODUCTION

The teacher reviews the previous lesson on Algorithms

Students pay attention

STEP 2

EXPLANATION

He explains the meaning of flowcharts and states the functions of flowcharts

 

Students pay attention and participates

STEP 3

DEMONSTRATION

He lists and explains the meaning of the flowchart symbols. He further describes the characteristics of a good flowchart and explains the steps in designing one

Students pay attention and participate

STEP 4

NOTE TAKING

The teacher writes a summarized note on the board

The students copy the note in their books

 

NOTE

ALGORITHMS AND FLOWCHARTS

When an algorithm is described or represented with symbols, it is called a flowchart. A flowchart is a diagrammatic or pictorial representation of an algorithm. It is a set Symbols used to describe the steps to follow when solving a specific problem.

 

Flowcharts use simple geometric symbols and arrows to define relationships.

 

FUNCTIONS OF A FLOWCHART

  1. It gives a snapshot view of the entire program, i.e. it gives flesh to the logic behind a program.
  2. It provides a pictorial summary of the step by step process involved in a program. This helps in the design of a program’s interface.
  3. It helps to troubleshoot programs easily, i.e. users or programmers can easily find mistakes and correct them.
  4. When used as an aid for training, a nicely laid out flowchart is visually stimulating

i.e. it gains and holds the reader’s attention and it is easy to understand.

  1. It helps to create an efficient work flow management that leads to continuous improvement.
  2. It ensures that customers’ needs within an organisation are met. This is achieved by organising into the business processes flowchart so that waste and inefficiency can be identified and corrected or eliminated.

 

CHARACTERISTICS OF A FLOWCHART

  1. Vertical Design: Every flowchart is designed or constructed vertically from top to bottom.
  2. Different Symbols: Each instruction or operation to be performed is represented with a different symbol.
  3. Directional Arrows: Arrows are used to show the flow and direction of instructions.
  4. Terminal Points: Every flowchart has a start point and an end point.

 

GUIDELINES OR RULES FOR DESIGNING FLOWCHARTS

Having been conversant with many of the flowchart symbols, it is now important to learn how to use them in designing flowcharts for the written algorithms. However, to be able to do this perfectly, users need to know and understand certain rules that deserve some respect in flowcharting and stick to them.

  1. All the important requirements in the program should be listed out in logical order.
  2. Flowcharts should be clear, neat and easy to follow i.e. there should not be an ambiguity (confusion) in understanding the flowchart.
  3. The flowcharts should flow either from left to right or top to bottom, i.e. it should have a particular direction.
  4. Only one flow line should come out from a process symbol.
  5. Only one flow line should enter a decision symbol. Two or three flow lines, one for each possible answer can leave the decision symbol.
  6. Only one flow line is used in conjunction with terminal symbol.
  7. Use short write ups in flowchart symbols. When necessary, use the annotation, symbol to describe data or computational steps in detail.
  8. In complex flowcharts, use connector symbols to reduce the number of flow lines. Also avoid the intersection of flow lines to make a more effective and better way of communication.
  9. Ensure that the flowchart has a logical start and finish or end.
  10. Test the validity of the flowchart by passing through it with a simple test data.

 

FLOW CHART SYMBOLS AND THEIR MEANING

 

WRITING ALGORITHMS AND DESIGNING FLOWCHARTS FOR SOLVING PROBLEMS

Example 1: Write an algorithm to calculate the sum of two numbers and design its flowchart

Solution:

EVALUATION:   1. Explain the meaning of flowchart

  1. State three functions of flowchart
  2. What are the characteristics of a good flowchart?
  3. List and explain the steps in designing a flowchart
  4. Write a simple algorithm and design a flowchart for the      problem below

                             Find the average of two numbers

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively