# Directed Number Lesson 4: Snakes on the Plane

Australian curriculum number (ACMNA124; ACMMG142)

## Lesson abstract

Lesson abstract Students begin by seeing the difference between coordinates on a street map (which they will be familiar with) and the new system of coordinates on a Cartesian plane. By understanding the Cartesian plane as a vertical and horizontal number line put together, students become familiar with how to use coordinates to describe position of points. They consolidate this knowledge by playing a game and extend it by creating geometric designs.

## Mathematical purpose (for students)

To use the Cartesian plane to describe position accurately and effectively.

## Mathematical purpose (for teachers)

This lesson introduces the Cartesian plane in all four quadrants. This knowledge is used to describe position. Students will understand the difference between a grid reference and the Cartesian system, and apply their knowledge of negative numbers from previous lessons. There are extension opportunities for students to discover how the coordinates of points are related when they construct symmetric designs, and when they move designs around on the plane.

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

• Understand the difference between a grid reference on a street map and the Cartesian system.
• Identify the four quadrants of the Cartesian plane.
• Describe points on the Cartesian plane correctly.