Lesson Notes By Weeks and Term v4 - JHS 1

Lesson Video

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Performance objectives

• Describe the coordinate plane, including the x-axis and y-axis.
• Plot points on a coordinate plane using ordered pairs.
• Plot basic geometric shapes on a coordinate plane.
• Understand the concept of translation.

Lesson summary

This lesson introduces the Cartesian plane, a powerful tool used to describe the exact location of points and shapes. In our daily lives in Ghana, we often need to give and follow directions. Think about using the GhanaPost GPS to find a house, locating a specific market stall in Makola or Kejetia, or even arranging chairs for a school assembly. All these activities use a system of location, just like the coordinate plane. By understanding how to plot points, we are learning the basic language of maps, design, and even computer graphics. This skill is a foundation for more advanced topics in mathematics and science.

Lesson notes

A. The Cartesian Plane

The Cartesian plane (or coordinate plane) is a flat surface formed by two number lines that cross each other at a right angle. It's like a map that helps us locate any point precisely. x-axis: This is the horizontal number line. It runs from left to right. Positive numbers are on the right of the starting point, and negative numbers are on the left. y-axis: This is the vertical number line. It runs up and down. Positive numbers are above the starting point, and negative numbers are below. Origin: This is the special point where the x-axis and y-axis cross. It is our starting point for all plotting. The location (or address) of the origin is (0, 0). Quadrants: The two axes divide the plane into four sections called quadrants. They are numbered using Roman numerals (I, II, III, IV) in a counter-clockwise direction, starting from the top right. Quadrant I: Top right (+x, +y) Quadrant II: Top left (-x, +y) Quadrant III: Bottom left (-x, -y) Quadrant IV: Bottom right (+x, -y) B. Coordinates as Ordered Pairs

Every point on the plane has a unique address called its coordinates. We write coordinates as an ordered pair of numbers in brackets, like (x, y). The first number is the x-coordinate. It tells you how far to move along the x-axis (left or right). The second number is the y-coordinate. It tells you how far to move along the y-axis (up or down).

Important Rule: The order matters! The x-coordinate always comes first. A good way to remember this is: "You must walk along the corridor (x-axis) before you can climb the stairs (y-axis)." C. How to Plot a Point