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Lesson Plan 56
Subject: Geometry
Date: January 9, 2008
SOL Objectives: G3, G4, G5,
Sponge Activities: The activity will include review problems from the midterm.
Introduction: We will review similar triangles by reviewing the last two homework
assignments in detail.
Direct Teaching:
I will introduce the concept of parallel lines within a triangle and how they form
similar triangles. If we have time after the homework review we will use protractors to
show that the angles within the triangles are equal and therefore similar.
The most important Theorem to teach in this chapter is the following:
Triangle Proportionality Theorem – If a line is parallel to one side of a triangle
and it intersects the other two sides in two distinct points, then it separates these sides
into segments of proportional lengths.
We will work on identifying whether triangles are similar or not. Students will be
shown several examples of how triangles can be similar using AA, SSS, SAS similarity
postulates.
Two angles are congruent by the SSS, SAS, and ASA postulates and the AAS Theorem.
In these triangles, corresponding parts must be congruent.
Two triangles are similar by AA similarity SSS similarity and SAS similarity. In similar
triangles the sides are proportional and the angles are congruent.
Guided Practice:
We will work on a guided practice 9-4 in the workbook page 50.
Independent Practice:
The above worksheet will be used for the independent practice as well.
Assessment:
I will use directed questioning to assess understanding.
Closure: I will summarize the lesson by reviewing information that was presented in
class.