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Lesson Plan: Lesson plans were written by Maryland mathematics educators and could be used when teaching the concepts.

Goal 2 Geometry, Measurement, And Reasoning

Expectation 2.2 The student will apply geometric properties and relationships to solve problems using tools and technology when appropriate.

Indicator 2.2.3 The student will use inductive or deductive reasoning.

Lesson Content

Different Methods of Construction

Objective

For the students to be able to perform geometric constructions using a variety of construction tools, investigate the properties of perpendicular bisectors and angle bisectors, and apply geometric constructions to real-life situations.

Other Indicators Addressed

2.1.4 The student will construct and/or draw and/or validate properties of geometric figures using appropriate tools and technology.

Approximate Time

Two to three 50-minute lessons or one to two 90-minute lessons

Prerequisite Concepts Needed

Basic vocabulary: line, line segment, angle, ray, distance, congruence, perpendicular, bisector, midpoint, distance between two points, distance between a point and a line, median of a triangle, altitude of a triangle
 
Students should understand the relationship of a figure and its image after a reflection over a line.

Materials Needed

Lesson Structure

    Essential Questions

    What are the measuring tools used in geometry?
     
    How and when are these measuring tools used in geometry?
     
    What are the construction tools used in geometry?
     
    How and when are these construction tools used in geometry?

    Warm-Up/Opening Activity

    Discuss how you would find the distance between two students in the classroom. Students should understand that distance is always measured as the shortest distance. The shortest distance between two points is the straight-line distance.
     
    Discuss how you measure the distance from a student in the classroom to a wall of the classroom. Students should understand that the shortest distance between a point and a line (or a plane) is the perpendicular distance from the point to the line (or plane).

    Development of Ideas

    Discuss the appropriate uses of geometric construction tools.
    A straightedge is only used for drawing line segments, not for measuring.
     
    A compass can be used for drawing a circle with a given center and a given radius measured from that center or to copy a line segment or transfer a distance from one place to another.
     
    Patty paper and Miras™ can be used to transfer distances or replicate congruent figures. They cannot be used for drawing circles.
    Replicate a segment using the different geometric construction tools.
    Worksheet: Review of Basic Constructions
     
    Worksheet: Patty Paper Investigations
    Determine right angles and perpendicular lines using patty paper. Questions 1-2
    Determine distance using patty paper. Questions 3-6
    Determine whether figures are congruent using patty paper. Question 7
    Create congruent figures using patty paper. Question 8
     
    Construct perpendicular lines and angle bisectors using patty paper.
    Worksheet: Constructions Using Patty Paper
     
    Construct perpendicular lines and angle bisectors using a compass and straight edge.
    Worksheet: Constructions Using Compass and Straight Edge
     
    Construct perpendicular lines and angle bisectors using a Mira.
    Worksheet: Constructions Using Miras
     
    Worksheet: Constructions
    Note: This activity could be completed as a jigsaw activity. Students could complete one or two of the problems, assigned by the teacher. The students could then share their solutions with the class in the next lesson.

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