Virginia SOL 5.MG.3.c
The Standard
Identify congruent sides and right angles using geometric markings to denote properties of triangles.
Virginia Standards of Learning for Mathematics · The student will classify and measure angles and triangles, and solve problems, including those in context.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students read tick marks as evidence that sides have equal length and a small square as evidence of a 90° angle. They place these symbols accurately and use them to describe a triangle's known properties.
What Mastery Looks Like
- Given a marked diagram, the student names the side pair sharing the same tick pattern and the vertex with a square corner. The student also places correct symbols when told two sides are equal or an angle measures 90°.
Common Misconceptions
- Students may judge sides by appearance instead of reading the marks. They may match sides with different numbers of ticks, or mistake an angle arc for a right angle square. Some place the square on a side rather than inside the angle at the vertex.
How to Assess It
- Exit ticket: Show triangle ABC with matching tick marks on AB and AC and a square at A. Ask students to name the congruent sides and right angle.
Lesson moves
Ways to Teach It
Give students paper triangles, rulers, and corner templates; they measure equal sides and right angles, then add matching tick and square marks.
Display a triangle that looks isosceles but has no tick marks, and ask, “What can we prove from the diagram alone?”
Run a card match where students pair triangle diagrams with property cards, using only repeated tick marks and right angle squares as evidence.
Show a roof truss photo; students mark verified equal beams and right angle joints after checking the listed measurements.
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Related Standards
- 4.MG.5.e
Denote properties of quadrilaterals and identify parallel sides, congruent sides, and right angles by using geometric markings.
- 7.MG.2.a
Identify corresponding congruent angles of similar quadrilaterals and triangles, through the use of geometric markings.
- 6.MG.4.c
Determine the congruence of segments, angles, and polygons given their properties.
- 7.MG.2.b
Identify corresponding sides of similar quadrilaterals and triangles.
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