TEACHER'S ACTIVITIES STUDENTS' ACTIVITIES
INTO:
-pair up students as they enter the classroom
-sit with assigned partner
tip: students will later be grouped into fours, so it
may help to
group them into fours at
this point depending on how focused
the students are in larger
groups
-pass out angle worksheet and read instru
-students complete worksheet
-get class back together after a few minutes of discussion
-refocus attention to teacher
-ask students about what they discussed
tip: encourage students to pay careful attention
to ratios
THROUGH: Lesson
-Definition of Similarity:
Triangle ABC ~ Triangle DEF iff AB/DE=BC/EF=CA/FD
and
-take notes and answer questions
m<A=m<D, m<B=m<E, m<C=m<F
tip: it is a good idea to make a list
of new and uncommon symbols
such as
similar(~), measure(m), and angle(<)
-found that AAA results in similarity, what about AA?
AA Similarity Postulate:
If two angles of one triangle are equal to two angles
of another
triangle, the triangles are similar
tip: illustrate each postulate/theorem
with examples
-are all congruent triangles similar?
SSS Similarity Theorem:
If the lengths fo the sides of one triangle are
proportional to the
lengths of the sides of a second triangle, then
the triangles are
similar.
SAS Similarity Theorem:
If an angle of one trianlge is equal to an angle
of a second
triangle, and if the lengths of the sides including
these angles
are proportional, then the triangles are similar.
-if 2 triangles are similar to the same triangle are they similar
to one another?
tip: at this point, it is beneficial
to make a list of
the ways to prove triangles are similar
Activity
-take students outside to side of the building where the sun is
casting its shadow
-participate in and think about group activity
-group students into fours
-ask one student in each pair to stand so that the end of his or
her shadow ends where the building's does
-another student will measure the length of the student's
shadow and height
-a third student will measure the length of the building's shadow
-the fourth student will record the data
-ask students to determine what the height of the building is
BEYOND:
-journal entry: What have you learned today?
What concepts were the most difficult for you? Do you need more practice
with them?
When will you use or have you used these concepts (outside of the class)?
-homework sheet
Accommodations:
Different types of learner may need certain adjustments
throughout this lesson. For auditory learners, a teacher should read
through the instructions with the entire group first. Also, during
the lecture portion of this lesson, notes should be both written on the
overhead/chalkboard and spoken. Kinesthetic learners may benefit
from having pipe cleaners to maneuver during the lecture on the theorems.
Students with disabilities should also be considered.
If a student is unable to work with a pencil to trace the angles, it is
possible for the students to create the triangle using Geometer's Sketch
Pad. The student can also be teamed up with another student and share
a triangle within a group of three.
Given the various roles for the outside activity,
there will most likely not be a problem get all students involved.
However, there is the possibility of poor weather. If this is the
case, simply do the activity with a strong flashlight or floodlight inside.
Standards:
This lesson was written in accordance with both
the NCTM and ISBE Standards. Topics of geometry and measurement
are explored through hands-on activities in which students engage in problem-solving.
Students are also required to make connection between the theorems
that have been introduced to and facts that they have. Finally, students
are asked to communicate their reasoningboth in writing and
orally.
Day
5 - Congruent Triangles 2
Teacher
Component Page
Day
7 - Concluding Activity![]()