Download 8.G.5 11.29.12

CC.8.G.5
2012
Domain: Geometry
Cluster: Understand congruence and similarity using physical models, transparencies, or geometry software
Standards: 8.G.5 Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the
angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles
Essential Questions
What can you conclude
about the angles formed by
parallel lines that are cut by
a transversal?
What can you conclude
about the measures of the
angles of a triangle?
How can you determine
when two triangles are
similar?
Content Statements
Identify parallel and
perpendicular lines formed
by a transversal.
Identify angles formed by a
transversal.
Find unknown angles.
Identify possible side
lengths in triangles.
Enduring Understandings
Two parallel lines cut by a
transversal create:
1. Corresponding angles
2. Vertical angles
3. Alternate Interior angles
4. Adjacent angles
5. Supplementary angles
6. Alternate Exterior angles
7. Same Side Interior angles
Activities, Investigation, and Student Experiences
Have students write a set of instructions that describe how to
create a pair of parallel lines cut by a transversal. Have students
read their instructions aloud to a partner and have the partner
follow the instructions to ensure that they are accurate.
Break students into groups. Provide students with pipe cleaners
or spaghetti to create a set of parallel lines cut by a transversal.
Hold a class discussion about what students notice about the
diagram. Then have students use a protractor to measure the
angles. Discuss the types of angles that are formed.
Show drawing of a square, rectangle, and a parallelogram. Ask
the students, “If a diagonal is drawn in each figure, what types
of triangles will be created?”
CC.8.G.5
Assessments
In the figure, angles A,D,E and H are all congruent, and
angles B,C,F and G are all congruent. Does this mean that
line 1 is parallel to line 2?
Equipment Needed:

LCD Projector

Document Camera

Internet Access

Spaghetti or Pipe Cleaner
Teacher Resources:
www.khanacademy.org
www.kutasoftware.com
www.ixl.com
www.njctl.org
www.nlvm.usu.edu
2012