Florida B.E.S.T. MA.8.GR.2.4
The Standard
Solve mathematical and real-world problems involving proportional relationships between similar triangles.
Florida B.E.S.T. Standards for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students identify corresponding sides in a pair of similar triangles and calculate the scale factor. They use equivalent ratios or equations to find missing side lengths in diagrams and real situations.
What Mastery Looks Like
- A student matches vertices correctly, writes a valid proportion, and solves for an unknown side length. The student labels units and checks that every side changes by the same factor.
Common Misconceptions
- Students often pair sides based on position rather than matching vertices. They may reverse one ratio but not the other. Some use addition instead of multiplying by the scale factor.
How to Assess It
- Exit ticket: Triangle ABC has sides 6, 8, and 10. Similar triangle DEF has a corresponding shortest side of 9. Find the other two sides and show one proportion.
Lesson moves
Ways to Teach It
Give pairs of paper triangles. Students measure each side, match corresponding sides, and record the three side-length ratios.
Ask, “How can you prove your proportion matches the correct sides?” Students write a claim and support it with labeled ratios.
Run a card match where students pair triangle diagrams, scale factors, proportions, and missing-length answers, then check with a partner.
Measure a student’s height and shadow, then use a meter stick’s shadow and similar triangles to estimate a flagpole’s height.
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Printable MA.8.GR.2.4 Worksheet
A ready-to-print activity worksheet aligned to MA.8.GR.2.4, with an answer key for the teacher on its own page. No account needed.
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Related Standards
- MA.912.T.1.2
Solve mathematical and real-world problems involving right triangles using trigonometric ratios and the Pythagorean Theorem.
- MA.912.GR.1.3
Prove relationships and theorems about triangles. Solve mathematical and real-world problems involving postulates, relationships and theorems of triangles.
- MA.912.T.1.8
Solve mathematical and real-world problems involving one-variable trigonometric ratios.
- MA.7.AR.4.5
Solve real-world problems involving proportional relationships.
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