# Directed Number Lesson 1: Elevator Challenge

Australian curriculum number (ACMNA124)

## Lesson abstract

Students develop a strong mental model of negative integers by playing a game that involves moving an elevator up and down in a hotel. By interpreting negative numbers as describing both a distance and a direction (below the lobby) they will understand their ordering and be able to reason about their properties (e.g. to find distances between them).

## Mathematical purpose (for students)

There are numbers below zero.

## Mathematical purpose (for teachers)

In this lesson, students develop a mental model of positive and negative integers that they can carry with them to understand later work with negative numbers. This lesson focusses just on the ordering of negative integers and not their ‘size’. Students will see patterns that help movement between positive and negative integers, interpreted in the elevator context.

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

• Show that there are numbers less than zero.
• Move between positive and negative integers.
• Understand how negative numbers are arranged on the number line.