Lesson
Plan
Subject/Topic:
Math/Complimentary, Supplementary, and Triangle Angles
Time (minutes) required for lesson: 135 minutes
CC
Georgia Performance Standards for this lesson:
MCC7.G.2.
Draw (freehand, with ruler and protractor, and with technology) geometric
shapes with given conditions. Focus on constructing triangles from three
measures of angles or sides, noticing when the conditions determine a unique
triangle, more than one triangle, or no triangle.
MCC7.G.5.
Use facts about supplementary, complementary, vertical, and adjacent angles in
a multi-step problem to write and solve simple equations for an unknown angle
in a figure.
Essential Question(s):
·
How can protractors be used to create and describe
angle measurements?
·
How can angle relationships be described as
supplementary or complimentary?
·
Why does the sum of the angles within a triangle
always equal 180 degrees?
Purpose/Relevance:
·
Understanding
relationships between angles is necessary to facilitate missing angle
measurement problem solving later in the geometry curriculum.
Goals of lesson aligned with CC
Georgia Performance Standards:
·
Students
will accurately find angle measurements using protractors.
·
Students
will determine angle relationships as being complimentary and/or supplementary.
·
Students
will understand the relationship between the sum of angles in a triangle and
supplementary angle measurements.
Materials/Equipment/Technology
Required:
·
< 10 geo-boards
·
< 100 rubber bands
·
< 2 sets of “ang-legs” (Substitute with Popsicle sticks, etc., if necessary)
·
Class
set of protractors
·
Paper
and pencils
PROCEDURES
Introduction: 20 minutes
Protractor Review I DO- WE DO- YOU
DO format. This is a general review for using protractors, because students
should have already been exposed to this already. Students need to know how to
use protractors so that they can explore the properties of angles and identify
relationships between angles later on.
·
Ask students: What is the protractor used for
when making shapes? (Expected response would be to measure angles.)
* I do- We do- You do:
Exercise for protractors*
o Estimate to one or two degrees.
1.
I do: Several examples from:
http://www.amblesideprimary.com/ambleweb/mentalmaths/protractor.html (This website is just a digital
version of a protractor. The teacher can set parameters as to the degree of
accuracy accepted for determining angle measurements using a protractor, as
well as other versions of protractor usage outside of finding angle
measurements.)
2.
We do: (On the white board with the wooden protractor)
§ Make a 45 degree angle.
§ Make a 105 degree angle.
3.
You
do:
§ Make an acute, obtuse, and right
angle.
Format of
the lesson- Direct Instruction: 15 minutes
1.
Supplementary and complementary note taking-
definition, examples, and real-world examples. What are supplementary angles?
Give clue for the “S” in supplementary as being able to turn into an 8 for 180
degrees. What are complimentary angles? Give clue for the “C” in complimentary
as being able to turn into a 9 for 90 degrees.
2.
Review angle measurements of triangles by asking
students how many degrees are in a triangle and clarifying any misconceptions
that may occur.
3.
Provide detailed instructions for the following
independent “centers”. Students will
break into six groups (decided on by the teacher). There will be three centers
duplicated so that there will be two of each center ongoing at all times.
Co-teaching model will provide students with one teacher per three centers for
monitoring and assistance purposes. Directions for each center will be posted
at each individual center.
Centers:
Complimentary Angles, Supplementary Angles, and Angles of a Triangle (20 minutes for each center)
1. Geo-board
Supplementary Angles Task: Investigate what makes two angles supplementary.
a. Use a protractor to measure the angle
formed by one long rubber band
piece, stretched over at least 5 pegs. What kind of an angle is this called?
(Straight angle).
b. Create a scalene triangle using the original long rubber band piece
(straight angle), and two shorter pieces and then add a fourth orange piece to
the center of the long rubber band piece, up through the vertex of the shorter
two rubber band pieces.
c. Remember how many degrees were in the
straight angle formed by the first single long rubber band. Measure and record
each of the angles formed at the center connector of the first long piece.
d. What do you notice about these angles?
How do they relate to the measurement of the degrees in the single long piece,
straight angle?
e. Try this again one more time with
different sized rubber band pieces. Is there a similar relationship?
f. What kind of angles are these?
Geo-board
Complimentary Angles Task: Investigate complimentary angles.
g. Make
medium-large sized square to begin.
h. Measure
and record the angle at the lower left vertex. *Use the protractor to measure
angles.
i.
Use
another connecting piece to divide the angle you just measured into two angles
as shown.
j.
Measure
both angles created by the new connecting piece, the angle bisector.
k. What
do you notice about these angles? How do they relate to the measurement of one
of the angles in the square?
l.
Find an equation that explains the mathematical relationship
between the original angle of the square and the two acute angles.
m. Try
this again one more time with different color pieces. Is there a similar
relationship?
n. What
kind of angles are the two acute angles?
2. “Ang-Legs” Triangle Sum Task: Investigate
the properties of the angles of a triangle.
a. Build
three congruent scalene triangles.
b. Identify
a different vertex on each triangles (arrows).
c. Connect
all three vertices together and align triangle legs.
d. What
do you notice about the degree measurement when all three angles are connected?
e. Repeat
with equilateral and isosceles triangles.
f. Does
this work for all triangles, or only certain triangles?
Closure: 20 minutes
·
What
are supplementary angles?
·
What
are complementary angles?
·
How
many degrees are in a triangle?
·
Find
examples of complementary and supplementary angles in the classroom.