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Geometry 9-12 / Week 12 / Monday
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Week 12 · Modeling the Set and Opening Night

Monday

Every prop is a shape
// Every prop a shape, every plan a number
⏱ about 20 min

Monday: Every Prop Is a Shape

Comet stands on the finished set under the work lights. "Opening Night is Saturday. Everything we built is out here."

Wren walks the stage with the clipboard. "Column, stair unit, ramp, turntable, backdrop, honeycomb panel. What do you notice?"

"Every one of them is a shape we know," Comet says. "The column is a cylinder. The stair unit is a box."

"The ramp side is a right triangle. The turntable is a circle," Wren adds. "And the lamp dish is a parabola."

Nova hovers above the turntable and projects a shape over each prop. "Would you like a hint? A model keeps what matters and drops the rest."

"The column has a chip in it," Comet says. "The cylinder does not care. What can we make with that?"

"A whole set, on paper, with numbers," Wren says. "Our designer, model every piece."

Comet and Wren stand on the finished set under the stage lights with Nova above, the seats empty before Opening Night.

Modeling: pick the shape, keep the measures

A real prop is never a perfect shape. A model is the simple shape closest to it, with the few measurements that matter.

The column has a chip and a seam. As a cylinder it has only a radius and a height, and that is enough to find its volume.

Piece of the setModelMeasures (crew's own)What we can compute
columncylinderr = 20 cm, h = 90 cmvolume of foam
stair unitbox120 by 50 by 20 cmvolume of foam
ramp sideright trianglebase 240 cm, height 40 cmarea of plywood
backdroprectangle6 m by 4 marea of fabric
honeycomb tileregular hexagonside 10 cm, apothem 8.7 cmarea of one tile
turntablecircleradius 5 grid unitsequation on the stage grid

A solved problem to study

Wren models the ramp side. It is a right triangle with base 240 cm and height 40 cm. The top edge is the slope.

Area: half of 240 × 40 = 4,800 square centimeters. That is how much plywood each side needs.

Then the stair unit as a box: 120 × 50 × 20 = 120,000 cubic centimeters of foam.

Why does this work? Once the shape is chosen, the formula does the rest. The hard part is choosing well and measuring carefully.

WHICH SHAPE MODELS IT?
  • Read the question.
  • Tap your answer.
Which shape is the best model for the column?
Which shape is the best model for the stair unit?
Which shape is the best model for a honeycomb tile?
Which shape is the best model for the lamp dish?
MEASURES OF THE SET
  • Read the question.
  • Tap your answer.
The stair unit is modeled as a box 120 by 50 by 20 cm. What is its volume in cubic centimeters?
A triangle with base 240 cm and height 40 cmThe ramp side is a right triangle with base 240 cm and height 40 cm. What is its area in square centimeters?
A 6 by 4 m rectangle drawn on a gridThe backdrop is a rectangle 6 m by 4 m. What is its area in square meters?
A cylinder with radius 20 cm and height 90 cmThe column is a cylinder with radius 20 cm and height 90 cm. What is its volume in cubic centimeters? Use 3.14 for π.
StatementTrue or false?
A model keeps the measures that matter and drops small details like a chip.?
A chipped column cannot be modeled as a cylinder.?
The ramp side is modeled as a right triangle.?
The backdrop is modeled as a sphere.?
The stair unit holds more foam than the column.?
WHY THIS EXERCISEChoosing the right model is the first step of every plan the crew makes this week.
The ramp side is a right triangle, base 240 cm and height 40 cm. What is its area in square centimeters? Type the number.
WHY THIS EXERCISEThe plywood for each ramp side is the area of its triangle, nothing more.
Try it
Walk through one room and name the shape that models five objects: a lamp, a table, a cup, a book, a ball.
For one of them, measure what you need and compute its area or volume.
Draw the set from the front. Beside each prop, draw the simple shape that models it and label its measures.

Strong modeling, designer. Tomorrow the crew counts sheets, cups and seats per unit of space: density.