Summary: Students will describe and identify basic geometry ideas including line
segments, rays, lines, parallel lines, perpendicular lines, and midpoint. Students will describe
attribute of angles and measure angles.
Main Curriculum Tie: Mathematics Grade 4 Strand: MEASUREMENT AND DATA (4.MD) Standard 4.MD.6 Measure angles in wholenumber degrees using a protractor. Sketch angles of specified measure. Materials:
Attachments
Background For Teachers: Enduring
Understanding (Big
Ideas):
Geometric ideas can be
identified and described.
Essential Questions:
 Where are examples of lines, segments and rays, parallel and
perpendicular lines and midpoints found in the realworld?
 How does a midpoint compare to other points on a line segment?
 What units of measurement are appropriate for measuring
angles? When is an angle considered to be a right angle? An
acute angle? An obtuse angle?
Skill Focus:
Identify and classify
geometric figures using
information about their
characteristics
Vocabulary Focus:
Point, line, line segment, ray, parallel lines, perpendicular lines,
intersecting lines, midpoint, angle, vertex, degree, protractor,
acute, right, obtuse, congruent
Ways to Gain/Maintain Attention (Primacy):
contest, sorting, measuring, cooperative
learning, manipulative, music, movement, virtual manipulativesGeoboard
Instructional Procedures: Post all vocabulary using a mind map to help students connect the words to
their meaning.
Starter: How great is your memory from your past experiences
Contest? Try to match each word to the correct picture.
Lesson Segment 1: Where are examples of lines, segments and rays, parallel
and perpendicular lines and midpoints found in the realworld? How does midpoint differ from other points on a line?
This can be a contest where small groups compete to see how many they can name. As
you discuss the starter with the students, have them begin to fill in the Geometry
Words journal page (attached). Assign each team of students one idea from the starter
except “angle” to consider three realworld examples or situations. Select one person
from each team to share the examples, so the class can choose one of those to write
on their journal page. As you discuss the ideas, have students fill in their own words
and sketches.
Lesson Segment 2: Where are examples of angles found or used in the realworld?
Guessing game: Tell students you are thinking of one of the geometric ideas and
that you will point to some examples of that idea in the room. When they think they
might know what the idea you are thinking of is, they may write the idea down. After
pointing to several examples that suggest where an angle might be formed, ask for
responses. Ask students to describe attributes for some of the angles you pointed to
such as where the vertex point might be, or where the line segments are which form
the angle. Show the math symbol for angle.
Lesson Segment 3: How can I describe attributes of angles?
Without giving information have students sort angles by cutting out the cards on
the Angle Sort paper. Partners cut and sort, writing the rule for their sort. Then have
the partners compare their sorting to another pair. Discuss with class the sort
bringing them to the idea that angles can be described by the wideness or openness of
the angle. This wideness is the measure of an angle. Remind them that they may
have heard words such as acute, right or obtuse when describing angles.
Sing this song with the students:
Classifying Angles Song
(to the tune of Skip To My Lou. Lyrics by Linda Bolin)
Use arms to show each as the verse is sung.
I’m a little angle. I like me like that.
An ACUTE little angle, and I’m not fat.
I’m an alligators mouth or a witches hat.
I’m ACUTE. I’m less than 90.
’m a RIGHT angle, and I look square.
Look for a corner, and I’ll be there.
I’m a flag or a present. I’m everywhere.
I’m just RIGHT. I’m exactly 90.
I’m rather large, so I have pride.
I’m an OBTUSE angle. I’m big inside.
I’m a reclining chair or a door open wide.
I’m OBTUSE. I am more than 90.
Have students use Twocolor Circular manipulative to show attributes such as acute,
obtuse and right as you ask them to. (A twocolor manipulative can easily be made to
allow the students to demonstrate angles. Make a cut in two different colored small
plastic plates from the circumference to the center of the plate. Slide the two plates
together at the cut.) As they play with the twocolor manipulative, get students to notice that an angle is a turn. When the turn is less than 90, the angle is acute. You can have students act this out. Have a student put one hand on a chair and rotate around it. Have the class guess if the rotation was an acute, obtuse or right angle. If the subject comes up, let students know that angles that are 180 or more hae different names and we will learn those at a later time.
Have students resort the angles into acute, right and obtuse categories (if they did not
originally do so) and write the category on the back of the card.
Lesson Segment 4: What is the measure for a given angle?
Use the “Measuring Angles” investigation worksheet and protractors to become more
familiar with the protractor and to measure angles.
Practice:
Make a three column foldable (as shown below). The back side of the foldable can be
labeled “Measuring and Classifying Angles”. Have students use their protractors to
measure each of the angles from the sort cards. Then have them use the protractor to
sketch the angles in the appropriate column on the Foldable and label the measure of
each angle.
Using the TwoColor Circular manipulative again, call out angle degrees and have the
students rotate the sections of their plate to show an estimate for the measure.
Students will enjoy practicing angles measures using a virtual protractor by going to
this site:
http://www.kidport.com/Grade6/Math/MeasureGeo/MeasuringAngles.htm
Assessment: Have students complete the quiz attached
Attachments
Assessment Plan: performance task, assignments, observation,
questions, quiz
Bibliography: This lesson plan was created by Linda Bolin. Author: Utah LessonPlans
Created Date : Apr 21 2009 11:24 AM
