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Those Obtuse Angles are aCute, Right? Sheryl Davis
Those Obtuse Angles are aCute, Right?
Sheryl Davis
Content Area: Geometry and Measurement
Grade Level: 4th grade Summary: The purpose of this Instructional PowerPoint is to teach students how to classify angles as obtuse, right, or acute.
Learning Objective: Given a picture of an angle, students will classify the angle as obtuse, right, or acute with 100% accuracy.
Content Standard: GLE 0406.4.1 Understand and use the properties of lines, segments, angles, polygons, and circles.
Accomplishment: Identify acute, obtuse, and right angles in 2-dimensional shapes.
Let’s Begin
Angles are all around
us
The panes on a window
The frame on a gate
A suit lapel
What is an angle?
?
? ?
?
Two rays…
That share the same endpoint (vertex)…
Form an angle
The area inside the two rays makes up the INTERIOR ANGLE
Click on the interior angle (the green area) to learn more.
↗
→
↘
To infinity
Ready to move on?
When we measure an angle, we can classify it as:
RIGHTACUTE
OBTUSEAngle measures
90°
Angle measures less than 90°
Angle measures greater than 90°
RIGHT ANGLE
• A right angle is an angle measuring exactly 90°
ACUTE ANGLE
• An acute angle is an angle measuring less than 90°
OBTUSE ANGLE
• An obtuse angle is an angle measuring more than 90°
Go to the following websiteManipulate the angle to form
a right angle, acute angle, and obtuse angle
http://www.mathopenref.com/angleright.html
Click on the right angle And learn a song to help youRemember right, acute, and
obtuse angles
Time to play…
NAME
THAT
ANGLE!!!
Click on the correct name for the following angle
Right Angle Acute Angle
Obtuse Angle
OOPS!! TRY AGAIN
Click on the correct name for the following angle
Right Angle
Obtuse Angle
Acute Angle
OOPS!! TRY AGAIN
Click on the correct name for the following angle
Right Angle
Obtuse Angle
Acute Angle
OOPS!! TRY AGAIN
SummaryIn this lesson, students will have learned:
Angles are not just lines on a page. Everyday objects, such as a window pane or a frame on a gate, are made up of angles.
Two rays that share the same endpoint, or vertex, is an angle. The area between the rays is called the interior angle.
We can measure angles and classify them accordingly.
Right angles measure exactly 90°, acute angles measure less than 90°, and obtuse angles measure more than 90°.
Students will visit two interactive websites where they will explore the properties of an interior angle and manipulate the measurement of an angle to form right, acute, and obtuse angles. They will also visit a website that includes a song sung to the tune of Old McDonald to help them remember the properties of right, acute, and obtuse angles.
