Lesson Plan for SD 2.2/2.4 (50 minutes):

Target: I can find a missing angle in a triangle.

5 minutes Warm-up (notebook)10 minutes Investigate Angle Sum – Have each student complete the angle

measurements and sum for one triangle and then share answers with their group.

5 minutes Summarize sum of interior angles and show example of tearing method (tearing off all angles and putting them together to make180 degrees).

25 minutes Give students time to work on A (review answers). Model at least one part of B (writing equations and finding missing angles). Save some time to go through those answers in detail.

5 minutes Reminders:• Correct homework with key (puzzle)

Quick Start Expectations1. Learning Target: I can find the measurement of a

missing angle in a triangle!2. Fill in Learning Log HW:

1) Missing Angles in Triangles WS (Inv. 2 packet) -Odd Problems2) Complete 30 mins of MathXL

3. Warm-up:Simplify these expressions by combining like terms.Example: 2x + 4x 2x + 4x = 6x (simplified answer)

a. 8x + 5x + 9xb. 5x + 8 + 2x + (-10)c. -3y + 5x + 8y + 2x + 4z

35° 35°

110°

110°50° 20°

70°

55° 55°

30° 60°

90°

180°

Equation:

50 + 70 + ___ = 180

∠CBA =

Equation:

___ + ___ + ___ = ____

∠KJL =

Equation:

∠GQW =

x + 2x + 3x = 1806x = 180x = 30°, 2x = 60, 3x = 90

x + 2x + x – 20 = 1804x - 20 = 1804x = 200x = 50°, 2x = 100, x – 20 = 30

Do not measure!

30°

60°90° 50°

100°

30°

S

HW: 1) Missing Angles in Triangles WS (Inv. 2 packet) -Odd Problems

2) Complete 30 mins of MathXL