Lesson plan - Study Island



|Math Lesson: Angles |Grade Level: 8 |

|Lesson Summary: Students review complementary, supplementary, interior, exterior, and vertical angles. They then draw a transversal and calculate the exterior |

|angle measurements created. Advanced students play a Twenty Questions-type game to identify triangle measurements by asking about exterior angle measurements. |

|Struggling students play a Twenty Questions-type game to identify triangle measurements by asking about interior angle measurements. |

|Lesson Objectives: |

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|The students will know… |

|the differences between complementary and supplementary angles, interior and exterior angles, and vertical and adjacent angles. |

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|The students will be able to… |

|calculate the measurements of angles when parallel lines are cut by a transversal. |

|Learning Styles Targeted: |

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|Visual |

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|Auditory |

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|Kinesthetic/Tactile |

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|Pre-Assessment: |

|Use this quick assessment to see if students understand the differences between complementary and supplementary angles. |

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|Draw two complementary angles and two supplementary angles on the board. Asks students the differences between the pairs of angles. |

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|Note students who do not understand that the sum of the measures of complementary angles is equal to 90° and the sum of the measures of supplementary angles is |

|equal to 180°. |

|Whole-Class Instruction |

|Materials Needed: Protractors, colored pencils |

|Procedure: |

|Presentation |

|Point to an analog clock or draw one on the board. Ask students to give the degrees when the minute and hour hand are at the following times: 3:00 [90°], 6:00 |

|[180°], 12:30 [about 180°], and so on. |

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|Next, as you draw examples on the board, have students draw two perpendicular lines to make four right angles, an x- and y-axis. Ask what type of angles you have |

|created. [4 right angles] |

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|Review complementary and supplementary angles by drawing a line through the vertex to split each 90° angle into two 45° angles. Have students identify three pairs |

|of complementary angles and three pairs of supplementary angles. |

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|Confirm that students understand that angles formed by two intersecting straight lines and are opposite each other are called vertical angles and have the same |

|measures. |

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|Next, have students draw a line parallel to the x-axis that intersects the other lines to create triangles. Explain that a line that crosses other lines is a |

|transversal. |

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|Have students use a colored pencil to identify an interior angle (inside a triangle) and an exterior angle (outside a triangle). Ask what the sum of the measures |

|of an interior and an exterior angle is. [180°, which forms a straight angle] |

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|Guided Practice |

|Have students outline each triangle created by the transversal with a colored pencil. Have them measure the interior angles and confirm that the sum of the |

|measures of the interior angles of a triangle is always 180°. |

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|Independent Practice |

|Have students choose one triangle created by the transversal and, without measuring, calculate all of the exterior angles. Then have them find the sum of the |

|exterior angles. [360°] |

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|Have them answer whether the sum of exterior angles would always be the same regardless of a triangle’s interior angle measurements. [yes] |

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|Closing Activity |

|Ask students to suggest practical applications for understanding the relationships among angle measurements (building, creating artwork). |

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|Ask how you can figure out the measurement of a vertical, complementary, or supplementary angle if you know one angle measurement. |

|Advanced Learner |

|Materials Needed: Protractor |

|Procedure: |

|Have students apply understanding of angle measurements by playing this game. |

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|Have one person draw a figure (any type of triangle or quadrilateral) and measure its angles so that no one else can see it. |

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|Each of the other players takes a turn asking a question only about exterior angles, such as, “Does your figure have four exterior angles that each measure 135°?” |

|until the figure with the correct angle measurements is named. |

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|Have students explain their results and strategies. |

|Struggling Learner |

|Materials Needed: Protractor |

|Procedure: |

|Have student apply understanding of angle measurements by playing this game. |

|Have one person draw a triangle and measure its interior angles so that no one else can see it. |

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|Each of the other players takes a turn asking a question, such as, “Does your figure have an interior angle that measures 90°?” until the triangle with the correct|

|angle measurements is named. |

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|Have students explain their results and strategies. When they have finished, have them complete the independent practice activity. |

*see supplemental resources

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