Coordinate Plane Foundations
A free Pre-Algebra lesson from the “Coordinate Plane, Functions, and Slope” unit, with a worked example and practice problems including step-by-step solutions.
The coordinate plane uses two number lines. The x-axis runs left and right, and the y-axis runs up and down. An ordered pair is written (x, y), so the first number tells horizontal movement and the second number tells vertical movement.
What you'll learn
- Read ordered pairs
- Identify quadrants
- Use coordinates to describe movement
Worked example
Problem. What quadrant contains the point (-3, 5)?
- The x-coordinate is negative, so move left.
- The y-coordinate is positive, so move up.
- Left and up is Quadrant II.
Answer: Quadrant II
Practice problems
1. In the point (4, -2), what is the x-coordinate?
Show solution
- Warm-up: First identify exactly what the question is asking: In the point (4, -2), what is the x-coordinate?
- For signed numbers, track both distance from zero and direction so the sign of the answer makes sense.
- The x-coordinate is the first number.
- The first number is 4.
- Check the result by substituting or estimating: the response should match 4 and make sense in the original problem.
Answer: 4
2. In the point (-6, 3), what is the y-coordinate?
Show solution
- Warm-up: First identify exactly what the question is asking: In the point (-6, 3), what is the y-coordinate?
- For signed numbers, track both distance from zero and direction so the sign of the answer makes sense.
- The y-coordinate is the second number.
- The second number is 3.
- Check the result by substituting or estimating: the response should match 3 and make sense in the original problem.
Answer: 3
3. Which point is on the y-axis?
Choices: (0, 5) · (5, 0) · (3, 3) · (-2, 4)
Show solution
- Warm-up: First identify exactly what the question is asking: Which point is on the y-axis?
- Compare each answer choice with the calculation or rule, and eliminate choices that do not satisfy the condition.
- Points on the y-axis have x = 0.
- (0, 5) has x = 0.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: (0, 5)
4. Which quadrant contains (2, 7)?
Choices: Quadrant I · Quadrant II · Quadrant III · Quadrant IV
Show solution
- Core Practice: First identify exactly what the question is asking: Which quadrant contains (2, 7)?
- Compare each answer choice with the calculation or rule, and eliminate choices that do not satisfy the condition.
- Both coordinates are positive.
- Positive x and positive y is Quadrant I.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: Quadrant I
5. Which quadrant contains (-5, -1)?
Choices: Quadrant I · Quadrant II · Quadrant III · Quadrant IV
Show solution
- Core Practice: First identify exactly what the question is asking: Which quadrant contains (-5, -1)?
- For signed numbers, track both distance from zero and direction so the sign of the answer makes sense.
- Both coordinates are negative.
- Negative x and negative y is Quadrant III.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: Quadrant III
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