Virginia SOL 7.MG.3.c
The Standard
Given a diagram, determine an unknown angle measure in a quadrilateral, using properties of quadrilaterals.
Virginia Standards of Learning for Mathematics · The student will compare and contrast quadrilaterals based on their properties and determine unknown side lengths and angle measures of quadrilaterals.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students identify the quadrilateral and read its angle markings. They use properties such as a 360° angle sum, congruent opposite angles, supplementary adjacent angles, or right angles to find an unknown.
What Mastery Looks Like
- Students select a property that fits the named shape and diagram markings. They write a correct equation, find the missing angle, and explain why their answer works.
Common Misconceptions
- Students may use 180° as the angle sum instead of 360°. They may assume all angles are equal or confuse opposite angles with adjacent angles. Some trust the drawing instead of using labels and markings.
How to Assess It
- Exit ticket: A parallelogram has one angle measuring 68°. Find the adjacent and opposite angles, then name the property used for each.
Lesson moves
Ways to Teach It
Cut the four corners from paper quadrilaterals, fit them around a point, then solve a missing-angle card using the 360° sum.
Display a rhombus with one 72° angle and ask, “Which property finds each remaining angle, and why?”
Play Match Three: students pair a marked quadrilateral diagram, its property card, and the equation that finds the unknown angle.
Use a photo of a window frame, label three interior angles, and have students calculate the fourth angle needed for a square fit.
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Related Standards
- 7.MG.3.d
Given a diagram, determine an unknown side length in a quadrilateral using properties of quadrilaterals.
- 7.MG.2.g
Given angle measures in a quadrilateral or triangle, determine unknown angle measures in a similar quadrilateral or triangle.
- 5.MG.3.h
Solve addition and subtraction contextual problems to determine unknown angle measures on a diagram.
- 7.MG.3
The student will compare and contrast quadrilaterals based on their properties and determine unknown side lengths and angle measures of quadrilaterals.
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