Lesson Notes By Weeks and Term v4 - JHS 3

Lesson Video

This page supports the lesson note with a companion video and a short classroom-ready summary.

For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.

Performance objectives

• Define significant figures and decimal places.
• Identify the number of significant figures in a number.
• Express numbers to a specified number of significant figures.
• Apply this knowledge in real-life contexts.

Lesson summary

In our daily lives in Ghana, we often use numbers that are not exact but are close enough for a specific purpose. When we listen to the news, we might hear that the population of Accra is "about 4 million," not the exact figure. When a carpenter gives a quote, they might say the cost of wood is "around GHS 500." This process of simplifying numbers is called rounding. Today, we will learn two important methods for rounding integers: to a specific number of decimal places and to a specific number of significant figures. This skill is crucial for estimating, reporting large numbers clearly, and making sense of data in science, business, and everyday conversations.

Lesson notes

This lesson focuses on two ways to approximate integers: using decimal places and significant figures. Part A: Rounding Integers to a Given Number of Decimal Places (d.p.)

An integer is a whole number (e.g., 15, 204, -3, 0). By definition, it has no fractional or decimal part. So, why would we be asked to round it to a decimal place?

This is usually done to show a required level of precision. When you round an integer to a certain number of decimal places, you are adding a decimal point and zeros to the end of it.

The Rule: Write the integer. Place a decimal point after the integer. Add the number of zeros required by the question.