Navigation
Learn the parts of a coordinate plane including the x-axis, y-axis, and the origin.
Imagine you are a pirate who has found a treasure map, but there are no landmarks—only a grid of lines. How do you tell your crew exactly where the gold is buried without pointing? You use the power of the Coordinate Plane!
A coordinate plane is a flat surface formed by two number lines that cross each other at a right angle. Think of it like a map of a city. The x-axis is the horizontal line that runs from left to right. The y-axis is the vertical line that runs up and down. The spot where they meet is the most important point on the map: the origin. The origin is always written as because you haven't moved anywhere yet!
Quick Check
What is the name of the exact point where the x-axis and the y-axis cross?
Answer
The origin
To find a specific spot on the grid, we use an ordered pair. This is a pair of numbers written inside parentheses like this: . The first number is the x-coordinate. It tells you how far to move to the right from the origin. The second number is the y-coordinate. It tells you how far to move up. A great way to remember the order is: 'You have to walk to the elevator before you can go up!'
Let's find the point on our grid. 1. Start at the origin . 2. Look at the first number, . Move units to the right along the x-axis. 3. Look at the second number, . From where you are, move units up. 4. Mark your point! You have found .
Quick Check
In the ordered pair , which number tells you how many units to move up?
Answer
8
Sometimes, the point is already on the grid, and you have to figure out its 'address.' To do this, just reverse the steps! Look down from the point to the x-axis to find the first number. Then, look across to the y-axis to find the second number. Always write them inside parentheses with a comma in between, like .
There is a treasure chest on the grid. It is lined up with the on the bottom line (x-axis) and the on the side line (y-axis). 1. The x-coordinate is . 2. The y-coordinate is . 3. The ordered pair is .
A robot starts at the origin . It moves units right and units up. Then, it moves more units to the right. What is its final location? 1. First move: . 2. Second move: Add to the x-coordinate: . 3. The y-coordinate stays the same: . 4. Final location: .
Which axis runs vertically (up and down)?
Where do you always start when plotting a point?
The ordered pair is the same location as .
Review Tomorrow
In 24 hours, try to draw a small grid and label the x-axis, y-axis, and the origin without looking at this guide.
Practice Activity
Create a 'Secret Message' for a friend by listing 5 ordered pairs that, when connected on graph paper, draw a simple shape like a triangle or a square!