Geometry
Graphing Ordered Pairs
Plotting points on the first quadrant of the coordinate plane.
Locating a Point with Two Numbers
A single number line can locate any point along one direction. But think about locating a specific seat in a movie theater, or a specific square on a game board — one number alone isn't enough. What do you think it would take to pin down an exact location in two directions at once?
Definition — Coordinate Plane
The pair is called 'ordered' because the order genuinely matters — the point (2, 5) and the point (5, 2) are two completely different locations. To plot a point from an ordered pair, start at the origin, move right (or left, for a negative number) along the x-axis by the first number, then move up (or down) by the second number.
Worked Example — Plotting a Point from an Ordered Pair
Worked Example — Reading the Coordinates of a Plotted Point
Graph Visualizer
Domain & range
Evaluate a point
- x^2 = 0
Tip
Common Mistakes
Plotting the y-coordinate's distance first, moving vertically before moving horizontally.
Always move horizontally along the x-axis first, using the first number in the pair, and only then move vertically using the second number.
Swapping the x- and y-coordinates when reading a plotted point, describing (4, 3) as (3, 4).
The x-coordinate is always the horizontal distance from the origin, and the y-coordinate is always the vertical distance — check which direction was measured first before writing the pair.
Key Takeaways
- A coordinate plane locates points using two number lines — a horizontal x-axis and a vertical y-axis — meeting at the origin.
- An ordered pair (x, y) gives the horizontal position first, then the vertical position.
- Swapping the order of the two coordinates changes the point being described.
Summary
The coordinate plane extends a single number line into two dimensions, using ordered pairs to pinpoint exact locations — the same idea that could graph the related number patterns from earlier in this grade. The final lesson returns to shapes, organizing them into a hierarchy based on shared properties.
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