Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 1st Term
Week: 3
Age: 15 years
Duration: 45 minutes
Subject: Economics
Curriculum Theme: Economics
Previous Lesson: Basic Tools of Economic Analysis: Graphs, Charts and Tables.
Topic: Basic Tools of Economic Analysis
Subject Matter: Meaning of measures of central tendency; types (mean, mode, median); merits and demerits of mean, mode and median; simple applications of central tendency.

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define measures of central tendency.
Identify the types of central tendency: mean, median, and mode.
State the merits and demerits of mean, median, and mode.
Apply mean, median, and mode to simple economic data.

Affective Domain:

Show interest in analysing data before making conclusions.
Value accuracy and neatness when computing averages and presenting results.

Psychomotor Domain:

Compute mean, median, and mode from simple data sets correctly.
Arrange data in ascending order and present calculations clearly using tables.

Work cooperatively in pairs or groups to solve data problems.
Participate respectfully in class discussion on the best measure to use in different situations.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum
State Unified Scheme of Work
Recommended Economics textbook for Senior Secondary Schools (e.g., Essential Economics for SSS, Book 1)
Encyclopaedia Britannica: Mean (Mathematics)
Khan Academy: Summarizing Quantitative Data
Math Is Fun: Mean, Median, Mode

Instructional Materials

The teacher will teach this lesson with the aid of:

Charts showing mean, median, and mode with examples
Tables of simple economic data (prices, wages, outputs, test scores)
Board and markers/chalk
Calculator (optional)
Prepared worksheet containing short data sets for practice

Rationale for the Lesson

This lesson helps pupils summarise data with a single value that represents the whole set. It also helps pupils make sensible comparisons and conclusions from prices, wages, and other economic information.

Prerequisite/Previous Knowledge

Pupils can add and divide numbers, arrange values in order, and read information from simple tables.

Lesson Content/Board Summary

Basic Tools of Economic Analysis: Measures of Central Tendency

Meaning of measures of central tendency

Measures of central tendency are statistical averages used to find a typical or representative value of a set of data.

Types of measures of central tendency

The following are types of measures of central tendency:

Mean (arithmetic average)
Median (middle value)
Mode (most frequent value)

Mean

Mean is the sum of all values divided by the number of values.

The following are steps to calculate mean:

Add all the values together.
Count the number of values.
Divide the total by the number of values.

The following is an example: Daily sales (₦): 200, 300, 500, 500, 700. Mean = (200+300+500+500+700) ÷ 5 = 2,200 ÷ 5 = 440.

Median

Median is the middle value when data is arranged in ascending or descending order.

The following are steps to calculate median:

Arrange the data in order.
If the number of values is odd, pick the middle value.
If the number of values is even, find the average of the two middle values.

The following is an example: 4, 6, 8, 10, 12. Median = 8.

Mode

Mode is the value that occurs most often in a set of data.

The following is an example: 2, 3, 3, 5, 7. Mode = 3.

Merits and demerits of mean

The following are merits of mean:

Uses all values in the data.
Easy to compute and widely used.
Useful for further calculations and comparisons.

The following are demerits of mean:

Greatly affected by extreme values (very high or very low numbers).
May give a value that is not in the data set.
Not suitable for data with open-ended classes.

Merits and demerits of median

The following are merits of median:

Not affected much by extreme values.
Suitable for skewed data and income/wage data.
Can be used with open-ended class intervals.

The following are demerits of median:

Does not use all values in the data directly.
May be time-consuming when data is large because ordering is required.
Not easy to use for further statistical calculations compared to mean.

Merits and demerits of mode

The following are merits of mode:

Easy to identify in a data set.
Shows the most common or popular value.
Useful for selecting popular sizes or products in business decisions.

The following are demerits of mode:

May not exist if no value repeats.
May be more than one (bimodal or multimodal) which can confuse interpretation.
Does not use all values in the data.

Simple applications of central tendency in Economics

The following are simple applications of mean, median, and mode:

Finding average price of a commodity over a period.
Finding average income or average expenditure of households.
Using median income to represent typical income where few very rich persons affect the mean.
Using mode to identify the most common price, wage, or product size demanded.
Comparing class performance using mean or median scores.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids, Guided Practice, Group Work

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher writes a small set of prices on the board and asks pupils how to find a single value that represents the prices, then introduces measures of central tendency.
Pupils’ Activity: Pupils suggest “average” and mention simple ways they have used averages before.
Learning Point: Averages help summarise a set of data.

Step 2: Meaning and types of central tendency

Time: 6 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher defines measures of central tendency and lists the types (mean, median, mode) using a prepared chart.
Pupils’ Activity: Pupils copy the definitions and list the types with brief meanings.
Learning Point: Mean, median, and mode are common measures of central tendency.

Step 3: Teaching mean with examples

Time: 8 minutes
Teaching Skill: Demonstration
Teacher’s Activity: The teacher demonstrates how to calculate mean step-by-step using a simple data set and shows the working clearly on the board.
Pupils’ Activity: Pupils compute mean for a short data set provided by the teacher and compare answers in pairs.
Learning Point: Mean is obtained by total divided by number of values.

Step 4: Teaching median with examples

Time: 7 minutes
Teaching Skill: Demonstration
Teacher’s Activity: The teacher shows how to arrange data and find median for both odd and even number of values using examples.
Pupils’ Activity: Pupils arrange given numbers in order and find the median for one odd set and one even set.
Learning Point: Median is the middle value after arranging the data.

Step 5: Teaching mode with examples

Time: 5 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher explains mode and uses examples that show one mode and two modes, linking to “most common” in real life.
Pupils’ Activity: Pupils identify the mode from two short data sets and state whether each is unimodal or bimodal.
Learning Point: Mode is the most frequent value in the data.

Step 6: Merits, demerits, and applications

Time: 9 minutes
Teaching Skill: Discussion
Teacher’s Activity: The teacher displays charts of merits and demerits of mean, median, and mode and discusses when each is best used, then solves one practical problem involving prices or wages.
Pupils’ Activity: Pupils discuss examples and choose the most suitable measure for a given situation, then solve one practice question on central tendency.
Learning Point: Different measures suit different types of economic data.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define measures of central tendency.
List the three main types of measures of central tendency.
Compute the mean and median of this data set: 4, 6, 6, 8, 10.
State two merits and two demerits of mean or median.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 5 minutes
Teaching Skill: Summary and Reinforcement
Teacher’s Activity: The teacher summarises the meaning, types, merits/demerits, and uses of mean, median, and mode and gives an assignment: compute mean, median, and mode for two short data sets and state which measure is best for income data with very high earners.
Pupils’ Activity: Pupils copy the summary and assignment and ask questions where necessary.
Learning Point: Central tendency summarises data and supports correct economic decisions.

Lesson Keywords

Central Tendency – statistical average used to represent a data set with a single value.
Mean – sum of values divided by the number of values.
Median – middle value after arranging data in order.
Mode – value that occurs most frequently.
Extreme Value – very high or very low number that can affect the mean.
Data Set – a collection of numbers or observations.
Skewed Data – data with values clustered more on one side, often with extremes.

Differentiation

Support slower learners with smaller data sets and guided steps for ordering and division, while faster learners handle larger data sets and explain which measure is most suitable for different economic situations.

Note for teachers using this lesson plan

Use familiar economic examples such as prices, wages, and household spending to make central tendency meaningful. Emphasize correct ordering for median and careful handling of extreme values when discussing the best measure to use.