6.8.C
The Standard
write equations that represent problems related to the area of rectangles, parallelograms, trapezoids, and triangles and volume of right rectangular prisms where dimensions are positive rational numbers
Texas Essential Knowledge and Skills for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students turn diagrams and word problems into equations for area or volume. They choose the correct formula and substitute positive fractions or decimals for the dimensions.
What Mastery Looks Like
- A student selects the correct formula and substitutes each given dimension in the right place. The equation uses decimals or fractions correctly and labels area or volume with appropriate units.
Common Misconceptions
- Students may use base times height for a triangle without dividing by 2. They may forget parentheses in the trapezoid formula or use surface area instead of volume for a prism.
How to Assess It
- Exit ticket: A trapezoid has bases of 4.5 meters and 7.5 meters and a height of 3 meters. Write an equation for its area without solving.
Lesson moves
Ways to Teach It
Give pairs paper triangles, parallelograms, and trapezoids to cut and rearrange into rectangles, then write equations using measured fractional dimensions.
Ask students to explain why a triangle equation includes one-half and why a parallelogram equation does not.
Run a card sort matching shape diagrams, short word problems, formulas, and equations with fraction and decimal dimensions.
Use a classroom floor plan and a storage box, then have students write equations for floor area and box volume.
Keep exploring
Related Standards
- 5.4.G
use concrete objects and pictorial models to develop the formulas for the volume of a rectangular prism, including the special form for a cube (V = l x w x h, V...
- 7.9.A
solve problems involving the volume of rectangular prisms, triangular prisms, rectangular pyramids, and triangular pyramids
- 6.8.D
determine solutions for problems involving the area of rectangles, parallelograms, trapezoids, and triangles and volume of right rectangular prisms where dimens...
- 7.9.D
solve problems involving the lateral and total surface area of a rectangular prism, rectangular pyramid, triangular prism, and triangular pyramid by determining...
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