Virginia SOL 5.MG.2.b
The Standard
Estimate and determine the area of a right triangle, with diagrams, when the base and the height are given in whole number units, in metric or U.S. Customary units, and record the solution with the appropriate unit of measure (e.g., 16 square inches).
Virginia Standards of Learning for Mathematics · The student will use multiple representations to solve problems, including those in context, involving perimeter, area, and volume.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students identify the base and perpendicular height of a right triangle. They estimate and calculate its area, then record the answer in square metric or customary units.
What Mastery Looks Like
- Students make a reasonable estimate, then calculate the exact area using one-half times base times height. They identify perpendicular measurements and record answers in square units.
Common Misconceptions
- Students may multiply the base and height but forget to divide by two. They may use the hypotenuse as the height or label answers with linear units instead of square units.
How to Assess It
- Give an exit ticket showing a right triangle with a base of 8 centimeters and a height of 5 centimeters. Ask for an estimate and exact area with units.
Lesson moves
Ways to Teach It
Cut a 6-by-8-inch paper rectangle diagonally, compare the two triangles, then calculate each area and label it in square inches.
Write a response to: Why is a right triangle's area half the area of a rectangle with the same base and height?
Sort diagram cards into matching estimate, exact area, and unit cards, then explain one match to a partner.
Find the area of a triangular garden with perpendicular sides of 12 feet and 9 feet, then estimate how much sod is needed.
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Printable 5.MG.2.b Worksheet
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Related Standards
- 5.MG.2.a
Investigate and develop a formula for determining the area of a right triangle.
- 8.MG.4
The student will apply the Pythagorean Theorem to solve problems involving right triangles, including those in context.
- 8.MG.4.d
Determine the measure of a side of a right triangle, given the measures of the other two sides.
- 8.MG.4.c
Identify the parts of a right triangle (the hypotenuse and the legs) given figures in various orientations.
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