The basics of the coordinate plane, as explained by Khan Academy.
Grades 6 through 8 Material from CK-12Preview Assign
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Understand a rational number as a point on the number line. Extend number line diagrams and coordinate axes familiar from previous s to represent points on the line and in the plane with negative number coordinates.
Solve real?world and mathematical problems by graphing points in all four quadrants of the coordinate plane. Include use of coordinates and absolute value to find distances between points with the same first coordinate or the same second coordinate.
Use ratio and rate reasoning to solve real?world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations.
Recognize and represent proportional relationships between quantities.
Draw polygons in the coordinate plane given coordinates for the vertices; use coordinates to find the length of a side joining points with the same first coordinate orthe same second coordinate. Apply these techniques in the context of solving real?world and mathematical problems.
Use similar triangles to explain why the slope m is the same between any two distinct points on a non?vertical line in the coordinate plane; derive the equation y = mx for a line through the origin and the equation y = mx + b for a line intercepting the vertical axis at b.