Coordinate Plane — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
The point (3, 0) is located 3 units above the origin.
Corrected: The point (3, 0) is located 3 units to the right of the origin.
The x-coordinate 3 means move right, and the y-coordinate 0 means no upward movement, so the point is 3 units to the right of the origin, not above it.
2. Fix the sentence:
An ordered pair is written with the y-coordinate first, then the x-coordinate.
Corrected: An ordered pair is written with the x-coordinate first, then the y-coordinate.
Ordered pairs always list x first and y second, written as (x, y). The original had the order backwards.
3. Fix the sentence:
The x-axis runs vertically on a coordinate plane.
Corrected: The x-axis runs horizontally on a coordinate plane.
The x-axis is the horizontal line that goes left to right. The vertical line is the y-axis.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. In the ordered pair (9, 4), the y-coordinate is 4.
The y-coordinate is the second number in an ordered pair, so in (9, 4) the y-coordinate is 4.
2. The point where the x-axis and y-axis cross is called the origin.
The origin is the special point (0, 0) where the x-axis and y-axis intersect, and it is the starting point for plotting all other points.
3. To plot (0, 5), stay at the origin and move 5 units up.
The x-coordinate is 0, so you stay at the origin without moving right. The y-coordinate 5 tells you to move 5 units straight up.
4. The ordered pair for the origin is (0, 0).
The origin is where both axes meet, so both coordinates are zero, making it (0, 0).
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Explain why the order of numbers matters in an ordered pair. Use (1, 8) and (8, 1) as examples.
Sample answer: The order matters because the first number tells how far right to go and the second tells how far up. The point (1, 8) is 1 unit right and 8 units up, but (8, 1) is 8 units right and only 1 unit up. They are in completely different positions on the grid.
A good answer includes: The order matters because the first number tells how far right to go and the second tells how far up. The point (1, 8) is 1 unit right and 8 units up, but (8, 1) is 8 units right and only 1 unit up. They are in completely different positions on the grid.
2. A point has an x-coordinate of 0 and a y-coordinate of 6. Where is this point located on the coordinate plane?
Sample answer: The point (0, 6) is located on the y-axis. Since the x-coordinate is 0, you do not move right or left from the origin. You only move 6 units up, so the point sits directly on the y-axis.
A good answer includes: The point (0, 6) is located on the y-axis. Since the x-coordinate is 0, you do not move right or left from the origin. You only move 6 units up, so the point sits directly on the y-axis.