Florida B.E.S.T. MA.912.GR.5.2
The Standard
Construct the bisector of a segment or an angle, including the perpendicular bisector of a line segment.
Florida B.E.S.T. Standards for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students use tools such as a compass and straightedge, paper folding, or geometry software to divide segments and angles into equal parts. They choose valid arc intersections and explain why the construction works.
What Mastery Looks Like
- A student can complete each construction without relying on ruler measurements or a protractor. Construction marks remain visible, and the student uses equal lengths, equal angles, or equidistance to justify the result.
Common Misconceptions
- Students often draw a line that looks centered instead of using intersecting arcs. Some assume every segment bisector must be perpendicular, or confuse an angle bisector with a line perpendicular to one ray.
How to Assess It
- Give students one segment and one angle. Ask them to construct each bisector with a compass and straightedge, keep arc marks visible, and write one justification.
Lesson moves
Ways to Teach It
Use patty paper to fold a segment’s endpoints together and an angle’s rays together, then trace and verify each crease.
Ask students to explain why intersecting equal-radius arcs identify points that are equally distant from a segment’s endpoints.
Run a construction relay where pairs draw a card, complete the named bisector, and earn a point only after a partner verifies it.
On a town map, construct a road that stays equally distant from two schools, then explain why it follows the perpendicular bisector.
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Printable MA.912.GR.5.2 Worksheet
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Related Standards
- MA.912.GR.5.1
Construct a copy of a segment or an angle.
- MA.8.GR.1.4
Solve mathematical problems involving the relationships between supplementary, complementary, vertical or adjacent angles.
- MA.912.GR.6.1
Solve mathematical and real-world problems involving the length of a secant, tangent, segment or chord in a given circle.
- MA.912.GR.5.3
Construct the inscribed and circumscribed circles of a triangle.
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