Locating Points with Two Coordinates
Lumi stands on a giant floor grid in a sunlit map room, holding a glowing marker and pointing toward a spot marked with an X shape on the grid, with one foot planted firmly on the horizontal line.
- Explain what an ordered pair is and what each number tells you.
- Identify the x-axis and y-axis on a coordinate grid.
- Locate and plot a point on a coordinate plane using an ordered pair.
- Describe the order of steps: move along the x-axis first, then up the y-axis.
- Compare two ordered pairs and explain why switching the numbers gives a different location.
Key terms
- Ordered pair
- Two numbers that name one spot.
- x-axis
- The flat line going left and right.
- y-axis
- The line going straight up and down.
- Origin
- The spot where the two lines cross.
The Map Grid
A coordinate grid is like a map made of lines. The flat line going side to side is the x-axis. The straight up-and-down line is the y-axis. They cross at a special spot in the corner called the origin, written as (0, 0). We use this grid to find exact spots, just like finding a treasure on a map. Every spot has its own pair of numbers to name it.
Across Then Up
To find a spot, we use an ordered pair like (3, 4). The first number tells how many steps to go across to the right. The second number tells how many steps to go up. So go across first, then up! Say it like this: across the hall, then up the stairs. The order matters a lot. If you switch the numbers, you land at a totally different spot on the grid.
Worked examples
Plot the point (2, 3) on the grid.
- Start at the origin, which is (0, 0).
- Go across to the right 2 steps along the x-axis.
- Then go up 3 steps and mark your point.
Answer: The point is 2 right and 3 up.
Activity
Drag each treasure chest to the correct point on the coordinate grid using the ordered pair shown on its label.
Practice
Describe how to plot the point (4, 1) step by step.
Are (2, 5) and (5, 2) the same spot? Tell why.
Common mistakes to avoid
- Go up first then across.No. Always go across first along the x-axis, then go up.
- (3, 4) and (4, 3) are the same.No. The order matters, so they land on different spots.
Check your understanding
You want to plot the point (5, 2) on a coordinate grid. What do you do first?
A student plots (3, 6) and another plots (6, 3). Are these the same location on the grid?
Which ordered pair names the origin — the point where the x-axis and y-axis cross?
Recap
A coordinate grid uses an x-axis and a y-axis that cross at the origin. An ordered pair names a spot by telling you to go across first, then up. The order of the two numbers always matters.
Reflect
How could a grid help you find a hidden treasure on a map?