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4.1B Triangle Properties Teacher Candidate: Mary Takle Lesson Date: 1/3/2011 Cooperating Teacher: Dawn Withee Grade: 9-11 (mostly grade 10 students) School District: Edmonds School District School: Lynnwood High School University Supervisor: Andrea Escame-Hedger Subject/Grade Level: Geometry Unit: Triangle Properties Grouping for Instruction: Students will sit in heterogeneous groups of 3-4 and work cooperatively using the Complex-Instruction model. Objective(s)/Learning Target(s): Students will identify and classify triangles and explore triangle properties Standard(s): 3.A Know, explain, and apply basic postulates and theorems about triangles and the special lines, line segments, and rays associated with a triangle. Prior Learning: We explored types of triangles before winter break – now we will come up with the formal definitions for triangles. Homework: McDougal Little Geometry: pg 221: 14-16, 21-29 Materials/Preparation Needed: Task Card, Geometer’s Sketchpad Files, Pencil, Paper, Triangle Cards, small whiteboards & markers Assessment of learning: Formative: Discussion with groups as I circulate through the class during group work. Instructional Plan and Strategies Opener: No homework to check. Vocab Packet & Demos (20 Minutes) Explore: Pass out Task Card (20 Minutes) Wrap-up: Pass the white board Triangle Game (10 minutes) Pass the Whiteboard (WB) and the pen. The group draws the requested figureon the WB and the board is passed to the next group over to score. Each correct answer is scored 1 point for that group. The RM for neighboring group keeps a group’s score. The pen moves from one person to the next in the group and the next card is shown, so each group member is required to draw a figure. Scalene Triangle, Isosceles, Triangle, Isosceles Right Triangle, Obtuse Isosceles Triangle, Scalene Right Triangle, Equilateral Triangle, Equiangular Triangle, Scalene Acute Triangle, Right Triangle, Equilateral Right Triangle, Scalene Obtuse Triangle, Acute Isosceles Triangle, Equilateral Obtuse Triangle, Equilateral Acute Triangle Modifications (Gear Up/Gear Down): Gear-up - Problem 2 should challenge the groups who get through the first set of problems quickly. Gear-down - Groups might need support identifying which theorems to use. Vocab can be challenging for ELL students, so reminding them to refer to the packet should help. Reflection: Geometry 4.1 Task – Classifying Triangles Learning Objective: You will classify a triangle by the lengths of its sides and the measures of its angles. You will apply the Triangle Sum Theorem and Exterior Angle Theorem. Problem 1: In each figure, solve for the unknown variable(s). (Show your work!) Then, classify the triangle based on angles and sides. (2𝑥 − 2)° 24° 𝑥° 45° (2𝑥 + 18)° (3𝑥 + 6)° 25° 𝑦° 𝑥° 20° 𝑥° 43° 𝑦° 𝑦° 75° 𝑥° 64° 𝑥° Geometry 4.1 Task – Classifying Triangles Learning Objective: You will classify a triangle by the lengths of its sides and the measures of its angles. You will apply the Triangle Sum Theorem and Exterior Angle Theorem. Problem 2: Find the measure of each of the lettered angles in the diagram below without using a protractor. t m = ______ n = ______ p = ______ q = ______ r = ______ s = ______ t = _______ u = ______ ****Teacher Check Point**** Geometry 4.1 Task – Classifying Triangles Vocab & Demos Triangle Types of Triangles sides Scalene A polygon with 3 sides No congruent sides Isosceles 2 congruent sides Equilateral 3 congruent sides angles Acute Obtuse Right Equiangular Interior Angles 3 angles < 90° 1 angle >90° 1 angle = 90° 3 congruent angles = 60° The angles inside the polygon Exterior Angles The angles that form linear pairs with the interior angles of a polygon Triangle Sum Theorem (4.1) The sum of the measures of the interior angles of a triangle is 180° mABC = 36° mCAB = 125° mBCA = 19° A ..\Chapter 4\triangle sum.gsp B mABC + mCAB + mBCA = 180° C Geometry 4.1 Task – Classifying Triangles Exterior Angle Theorem (4.2) The measure of an exterior angle of a triangle is equal to the sum of the measures of the two non-adjacent interior angles. mABC = 76.0° mBAC = 58.4° mABC + mBAC = 134.4° A mACD = 134.4° ..\Chapter 4\exterior angle theorem.gsp B D C Corollary to Triangle The acute angles of a Sum Theorem right triangle are complementary mABC = 39° B mABC + mBCA = 90° mBCA = 51° ..\Chapter 4\right triangle.gsp A C Daily Plan Sheet Subject: Geometry Date: 1/3/2011 Lesson: Triangle Properties Goal(s)/Standard(s): You will classify a triangle by the lengths of its sides and the measures of its angles. You will apply the Triangle Sum Theorem and Exterior Angle Theorem. Look fors: Everyone working together Showing your work Group discussion Use of math vocabulary – scalene, isosceles, equilateral, acute, obtuse, right, equiangular, interior, exterior Today you will need someone who can… Write equations Solve equations Use theorems Analyze Understand vocabulary Ask “Why?” Say “Wait, I don’t understand!” Materials: Vocabulary sheets, task card, pencil, whiteboard, markers Pass the Whiteboard and the Pen Rules 1. Only the designated person can use the whiteboard marker. The other group members are permitted to talk, but not draw. 2. No pencils/pens on the table. You may use your vocab sheets. 3. Your team has one minute to come up with the drawing. 4. At the end of one minute, your white board must be passed to the group that is designated to score your answer. 5. The Resource Manager keeps track of the score. 6. Each correct answer is worth 1 point. No partial credit. 7. For each new problem, the whiteboard and pen rotate to the next group member. Task – Communication – Resource – Norm. 8. No sharing answers outside your group. 9. Teams caught cheating will lose one point. Rotation pattern 8 7 6 4 3 2 5 1 Scalene Triangle Isosceles Triangle Isosceles Right Triangle Obtuse Isosceles Triangle Scalene Right Triangle Equilateral Triangle Equiangular Triangle Scalene Acute Triangle Right Triangle Equilateral Right Triangle Scalene Obtuse Triangle Acute Isosceles Triangle Equilateral Obtuse Triangle Equilateral Acute Triangle Equiangular Scalene Triangle Equiangular Isosceles Triangle Exterior angle of a triangle Interior angle of a triangle