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Geometry and Measurement 6-8 / Week 08 / Build Day
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Week 08 · Angles

Build Day

Build Day: The roof goes on
// Pairs that add up, pairs that match
⏱ about 20 min

Build Day: The Roof Goes On

Saturday at the Blueprint Table, the straw roof frame is ready. Rocket holds the peak truss up. "Sixty, sixty, sixty."

"Measure the slope where it meets the wall," Raven says. "A grown-up holds it still."

Rocket measures. "The rafter makes 60 with the wall top. So the other side is 120. Supplementary."

"And the brace across the two rafters?" Raven asks. "What do you notice before you measure?"

"Two sizes of angle," Rocket says. "I measure one and write all eight." He does. "Done in one go."

Nova hovers above the peak, her light steady on the three corners. "Check the sum before you glue," she says.

"180," Rocket says. Nova hums. "Then the roof goes on."

  1. Supplementary angles add to 180°, complementary angles add to 90°, vertical angles are equal, adjacent angles add to the whole.
  2. Write the rule as an equation with x, solve it, and check that the angles add back up.
  3. The three angles of a triangle add to 180°. Torn corners laid along a line show it.
  4. An exterior angle of a triangle equals the two far angles added.
  5. Parallel lines cut by a transversal make two sizes of angle. Corresponding angles are equal.
◇ FAMILY ANGLE HUNT
Together, find a triangle in the house: a shelf bracket, a sign, a folded napkin. Measure its three angles and add them.
Find a door standing partway open. Measure one angle with the wall and predict the other side.
Lay two pencils parallel and a third across. Measure one angle, then predict and check two more.
Hold the roof frame on the clubhouse walls while your student measures the slope angle. Then glue or tape it on.
For a grown-up
This week your student learned angle pairs, the triangle angle sum, exterior angles and angles on parallel lines.
Ask them why the three torn corners of any triangle make a straight line. The answer should mention 180°.
Hold the roof frame steady for measuring. Scissors only for straws and cardboard, with you nearby.
Safety first
Straws are cut with scissors, sitting down, with a grown-up nearby. No one runs holding a straw or stick.
Glue stays on the cardboard and off hands and faces. Wash hands after building.
BUILD DAY CHECK
  • Read the question.
  • Tap your answer.
Two angles side by side making 180°; one is 60° and the other is marked ?The rafter makes 60° with the wall top. What is the angle on the other side, in degrees?
A triangle with angles 60° and 60° and the third angle marked ?The peak truss has two 60° angles. What is its third angle, in degrees?
Two parallel lines crossed by a third line; angle a is 60° and the other angles are lettered b to hThe brace crosses both rafters. Angle a is 60°. What is angle h, in degrees?
A triangle with angles 60° and 60° and the exterior angle at the third corner marked ?The peak truss has far angles of 60° and 60°. What is the exterior angle at its peak, in degrees?
Build Day checkTrue or false?
60 + 60 + 60 = 180?
A rafter at 60° to the wall leaves 120° on the other side.?
The brace makes eight angles of eight different sizes.?
WHY THIS EXERCISEEvery angle on the roof was found from one or two measurements, which is what the week was about.
Draw the clubhouse roof from the side: two rafters, the brace across them, and every angle labeled.

Great building, crew. Next week: slides, flips and turns, and a tile pattern for the clubhouse floor.

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