First Quadrant Coordinates
Describe positions on a 2-D grid as coordinates in the first quadrant
Ce que l'enfant saura faire ensuite
- Read the coordinates of a point on a grid as (3, 5)
- Explain that the first number is the horizontal distance and the second is the vertical distance
- Identify the coordinates of all vertices of a shape plotted on a grid
- Use two coordinates on the same grid line to find a side length or the middle of an edge, such as the bottom side from (1, 1) to (6, 1)
1 · Lis
A grid is a flat space covered in crossing lines that make little squares. You can point to any spot on the grid using just two numbers, so you can tell a friend where treasure hides on a map. Those two numbers are called coordinates: across first, then up. The across number is also called the x-coordinate, and the up number is the y-coordinate.
Ravi is playing a treasure map game. The treasure is 4 steps across and 3 steps up from the corner of the map. Ravi writes this as the coordinates (4, 3): first the across number, then the up number. The corner where counting starts is (0, 0).
From (2, 1) to (8, 1), the side length is 8 minus 2 = 6 squares. Halfway between 2 and 8 is 5, giving midpoint (5, 1). For an upright side, subtract the up numbers instead.
Both ends share the up number 1. The middle sits halfway along, at (5, 1).
Always read the numbers in order: across first, then up. If you say them backwards, you can point to the wrong spot.
Coordinates name a spot with two numbers: across first, then up.
À lire aussi
Coordinate plane word problems practice (quadrant 1)
The first quadrant is the corner of the grid where both numbers are positive. You start at zero and count along to the right, then count up. A story about a treasure 3 along and 5 up leads to the point (3, 5). The order always matters: along first, then up. Word problems hide coordinates inside stories about maps, parks and treasure hunts. Pull out the two counts, write them as a pair with the along number first, and plot the dot. Reading the story twice helps you catch which number goes first.
Graph points review (positive numbers only)
Plotting with positive numbers only keeps you in the first quadrant. Walk right from zero by the first number, then climb up by the second number. For (3, 5), walk 3 right and climb 5 up, then mark the dot. A common mix-up is plotting (5, 3) instead of (3, 5). Those are different dots in different places. Say the pair out loud as along then up before you mark it. That habit catches swaps before they happen.
2.1 The Rectangular Coordinate Systems and Graphs
A rectangular grid is built from two number lines that cross at zero. The flat line measures the horizontal distance, and the upright line measures the vertical distance. Every point gets a pair: the horizontal count first, the vertical count second. In (4, 1), the 4 counts along and the 1 counts up. Vertices of a shape are just its corner points, and each one gets its own pair. List every corner of a rectangle and you fully describe where it sits on the grid.
Key ideas: Draw lines in the coordinate plane and identify points on the lines
Lines on a grid pass through many points, and each point on the line follows its rule. If you draw a flat line at height 1, every point on it looks like (something, 1). Spotting the points that sit on a drawn line trains your eyes to read coordinates fast. Check each dot one by one: count along, count up, write the pair. Dots on the same flat line share their second number. Dots on the same upright line share their first number. Those shared numbers are clues that speed up reading whole shapes.
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