Florida B.E.S.T. MA.912.GR.3.4
The Standard
Use coordinate geometry to solve mathematical and real-world problems on the coordinate plane involving perimeter or area of polygons.
Florida B.E.S.T. Standards for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students plot polygon vertices and find side lengths from coordinates. They calculate perimeter by adding lengths and find area using formulas, decomposition, or subtraction from a bounding rectangle. They interpret answers using appropriate units.
What Mastery Looks Like
- Given polygon vertices, a student plots and connects them in the correct order. The student chooses an efficient method, calculates accurate side lengths and area, and labels answers with correct units.
Common Misconceptions
- Students may count grid units for a diagonal side instead of using the distance formula. They may confuse perimeter with area or use a base and height that are not perpendicular. They may also connect vertices in the wrong order.
How to Assess It
- Give the triangle A(1,1), B(7,1), and C(7,9). Ask students to find its perimeter and area and show how each value was calculated.
Lesson moves
Ways to Teach It
Plot a polygon on graph paper, measure each side with string, then verify the perimeter and area from the coordinates.
Ask students to explain why a diagonal side length cannot be found by simply adding its horizontal and vertical changes.
Give pairs of cards, one with polygon coordinates and one with its perimeter and area, then have teams find matching pairs.
Design a dog park on a coordinate grid, then calculate the fencing needed and the ground area to cover.
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Related Standards
- MA.912.GR.3.3
Use coordinate geometry to solve mathematical and real-world geometric problems involving lines, circles, triangles and quadrilaterals.
- MA.7.GR.1.2
Solve mathematical or real-world problems involving the area of polygons or composite figures by decomposing them into triangles or quadrilaterals.
- MA.912.GR.3
Use coordinate geometry to solve problems or prove relationships.
- MA.6.GR.1.3
Solve mathematical and real-world problems by plotting points on a coordinate plane, including finding the perimeter or area of a rectangle.
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