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Angles and Triangles. Terry Scates Newton, Kansas. Instructor Notes. Subject Area(s): Math Grade level: 7 th grade Lesson Length: 50 minute class period Synopsis: Name triangles by angles and sides.
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Angles and Triangles Terry Scates Newton, Kansas
Instructor Notes Subject Area(s): Math Grade level: 7th grade Lesson Length: 50 minute class period Synopsis: Name triangles by angles and sides. Objective/goals: Students will classify triangles according to types or angles and sides. (This PowerPoint presentation was designed as a supplemental piece to the presentation entitled Classifying Triangles by James Wiens for students in the special education math class.)
Standard: ▲ identifies angle and side properties of triangles and quadrilaterals (KS standard 7.3.1.k3) Pre-requisite skills: Vocabulary – Acute, Obtuse, Right, Equilateral, Isosceles, Scalene TurningPoint functions:standard question slides Materials: All instructional points and practice problems are provided within the power point slides. Practice questions are designed to be used with the TurningPoint clickers. (This PowerPoint presentation was designed as a supplemental piece to the presentation entitled Classifying Triangles by James Wiens for students in the special education math class.) Instructor Notes
Lesson Outline 1. Warm-up: Angle classification 2. Setting the Stage: 3. Guided practice: Turning Point Questions 4. Independent practice: Paper & pencil 5. Closure: Write about triangles
What we already know about angles: An angle has two sides that share a common endpoint.
What we need to know about angles: The point where the sides meet is called the vertex.
What we need to know about angles: • Angles are measured in degrees, where 1 degree is one of 360 equal parts of a circle.
Angles are classified according to their measure. An acute angle is less than 90° An obtuse angle is more than 90° A right angle is 90°
Right Angle Find some examples of right angles in the classroom:
Acute Angle Find some examples of acute angles in the classroom:
Obtuse Angle Find some examples of obtuse angles in the classroom:
Classify this angle: Acute Right Obtuse Answer Now Classify this angle: 10 Countdown
Classify this angle: Acute Right Obtuse Answer Now 10 Countdown
Classify this angle: Acute Right Obtuse Answer Now 10 Countdown
What we already know about triangles: • A triangle is a figure with three sides and three angles. • The symbol for triangle is
What we need to know about triangles: • The sum of the measures of the angles of a triangle is 180°. • You can use this to find a missing angle measure in a triangle.
Triangles can be classified by the measures of their angles.
Triangles can also be classified by the lengths of their sides.
Sides that are the same length are congruent segments and are often marked by tick marks.
Classify this triangle by angles and by sides Acute / Isosceles Obtuse / Isosceles Acute / Scalene Obtuse / Scalene Answer Now 7 70 4 40 70 7 10 Countdown
Classify this triangle by angles and by sides Acute / Isosceles Right / Isosceles Acute / Scalene Right / Scalene Answer Now 8 90 30 4 9 60 10 Countdown
Classify this triangle by angles and by sides Acute / Isosceles Obtuse / Isosceles Acute / Scalene Obtuse / Scalene Answer Now 14 130 6 15 35 18 10 Countdown
Classify this triangle by angles and by sides Acute / Isosceles Right / Isosceles Acute / Equilateral Obtuse / Scalene Answer Now 7 60 60 7 7 60 10 Countdown
You are ready to try on your own! • Think about what you have learned. • Think about what you already knew. • Think about what you can teach others.
Answer Key for Independent Practice Obtuse / Isosceles Acute / Equilateral Right / Isosceles Acute / Isosceles Obtuse / Isosceles Acute / Equilateral Obtuse / Scalene Right / Scalene
Closure/Summary • Is the sum of the angles of an obtuse triangle greater than the sum of the angles of an acute triangle? Explain your answer.
References Glencoe McGraw-Hill Math Connects Course 2, Study Guide and Intervention and Practice Workbook, 2008. Wiens, James, Classifying Triangles, PowerPoint presentation, November 2008.