Directed Number Lesson 3: Chill Out

Australian curriculum number (ACMNA124; ACMNA128)

Lesson abstract

Students will locate decimal numbers on a horizontal number line that extends below zero. They will complete a data table of positive and negative temperatures and temperature ranges for different cities around the world. They will represent temperature ranges on a horizontal bar graph to show the distance between positive and negative numbers. There are also options for students to work with heights above and below sea level, and credit and debit.

Mathematical purpose (for students)

To work with negative numbers in real situations.

Mathematical purpose (for teachers)

This lesson extends the students’ understanding of negative numbers. Students are required to apply knowledge of negative numbers to everyday situations, in this case looking at temperatures around the world. Temperatures are often expressed as decimals. Students explore the arrangement of decimals and negative numbers on the number line. They develop a meaningful strategy to calculate the difference between positive and negative numbers, some of which are whole numbers and some of which are decimals.

At the end of this lesson, students will be able to:

  • Use a horizontal number line.
  • Identify the positions of positive and negative decimals on a number line.
  • Use a number line to find differences between numbers, including decimals.