7th Grade Math

Suppose Mrs. Wendell’s class made a model of a

house. The model was composed of a rectangular

prism and a triangular prism. Create a model of the

building using centimeter cubes to find the volume

and surface area.

What do you need to find? the volume and surface area of the

model house

Model the top and bottom prisms using models.

3 cm

3 cm

4 cm

3 cm

4 cm

2.5 cm

2 cm

Copy and complete the tables using the models from Step 1.

Count the cubes to find the dimensions.

Length

(cm)

Width

(cm)

Rectangular

Prism

Bottom 4 3 3

Volume

(cm^3 )

Surface

Area (cm^2 )

Height

(cm)

Length

(cm)

Base

(cm)

Triangular

Prism

Top 4 3 2

Volume

(cm^3 )

Surface

Area (cm^2 )

Height

(cm)

Combine the volume for both prisms to find the total

volume of the model.

the Results

4. What is the total surface area of the model?


5. Describe a real-world situation where it might be necessary to use a
   model or drawing to find the volume or surface area.


6. MAKE A CONJECTURE How could you find the volume and surface area
   of a composite figure given all the measures?


7. Use the top, side, and front

top side front

view to build the figure using

centimeter cubes. Then make

a sketch of the figure. Find

the surface area and volume

of the figure.

3 cm

2 cm^2 .5 cm

4 cm

3 cm

Lesson 3B Composite Figures 605

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