L1 · The Coordinate Grid: Axes, Origin, Ordered Pairs

Learning goal

“I can name the parts of a coordinate grid - the vertical axis, the horizontal axis and the origin - and I can read and write an ordered pair (x, y) knowing that the first number tells the distance from the vertical axis and the second number tells the distance from the horizontal axis.”

Coordinate grid — two number lines crossed at right angles, making a grid where every point has an exact address.

Axis — one of the two number lines of the grid: the vertical axis runs up and down the left side; the horizontal axis runs left to right along the bottom. (Plural: axes.)

Origin — the point (0, 0) where the two axes cross; every location is measured from here.

Ordered pair — the address of a point, written (first number, second number): first the distance from the vertical axis, then the distance from the horizontal axis. The order matters - swapping the numbers moves the point.

Worked example

Build the grid from two number lines you already know. Step 1: Lay a number line flat along the bottom, 0 to 10. This is the horizontal axis. Step 2: Stand a second number line upright at the left end, also 0 to 10. This is the vertical axis. Step 3: The two axes cross at their zeros. That crossing point is the origin, and its ordered pair is (0, 0) - zero distance from both axes. Step 4: Wherever a vertical grid line and a horizontal grid line cross, there is a point with an exact location. Naming that location is the job of the ordered pair, which is Chunk B. Say it plainly: a coordinate grid is two number lines sharing one zero. Everything is measured from the origin.

Check yourself — explain it

The origin is the point where…

Paired problem — example still visible

Which axis runs up and down the left side of the grid? -> The vertical axis.

Faded completion — last step is yours

"The axis along the bottom of the grid is called the ___ axis." -> horizontal

Ready to practise?

10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.

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