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TG Grade 4 Classify Angles

Page history last edited by Sarah Juarez-Farias 10 years, 4 months ago


Submitted by:

Sarah Juarez-Farias



Edited by:

Julie Rape/Jennifer LIckert




Unit Name: Classification of Angles

Unit Length: 5 Weeks

Overview: Students will classify angles based on their attributes and justify their reasoning for each classification. They will find a reasonable measurement for angles based on the rules they apply for the classification process. They will also name the different parts of angles.


TEKS and SEs

(4.8)  Geometry and spatial reasoning. The student identifies and describes attributes of geometric figures using formal geometric Language. 

The student is expected to:

(A)  identify and describe right, acute, and obtuse angles;

Critical Vocabulary

angles, point, ray, acute, obtuse, right, greater than, less than, 90 degrees, reasonable,

Enduring Understandings (Big Ideas)

Students understand and identify angles based on their attributes.

Students can estimate the size of an angle based on what they know about acute, obtuse, and right angles. 

Essential Questions

What are the attributes of an acute, obtuse, or right angle? Can you identify some real world examples of these angles?


Learning Goals and Objectives

The student will correctly classify angles 95% of the time.

The student will correctly estimate the measurement of a non-right angle 85% of the time.

Materials Needed

Sorting angles and triangles, labels for each angle category,


Performance Tasks

Correctly forming the predetermined angles on an interactive circular geoboard.



Other Evidence

Discussion or explanation of attributes in a given category are observed by teacher.





Engage: Begin lesson with an angle sort. Working in groups, students will be given a set of angles that need to be sorted according to attributes. No criteria should be set. Students need to decide within their groups what attributes they deem important. Angles and triangles will be included in the sorting set. Students do not need to classify triangles by side length (scalene, isosceles, right).


Explore: Students will create criteria for each group of angles they have made. They should be asking themselves, “WHY?” they put each angle in the group it is in.


Explain: Groups then share-out their reasoning. Students will affix their angles to the whiteboard and label them according to their attributes. With each additional group that goes up, they may add to an existing category or create their own category. They can also change the explanation another group has presented. They may not disagree with a group unless they can provide a valid argument as to why it isn’t so.



Students return to their groups and teacher revisits each category on the board. Attributes are clarified and the category is named according to the attributes if this has not been done so already. Categories that should be combined are at this point. If any new categories should be created, they are. Each angle on the board is tested with a 90o corner of math chart as this is the tool they should use on the test.



Revisit the previous day’s lesson. Clear up any clear misconceptions students may have.

Students that are still struggling will be pulled into a small group while the remaining students move on the interactive activity. Once the group is successfully explaining how the attributes of an angle decide its classification, they may join the computer activity.


Visit the National Library of Virtual Manipulatives and enter the Geoboard circular activity.

Students must create examples of right, acute, and obtuse angles by using the virtual rubber bands on the circular geoboards.





20 min





15 min



30 min






25 min








30 min





60 min




Extend lesson to include the names of the triangles according to the length of the sides.





Students given an actual geoboard to practice finding differences in attributes, however, they must find all attributes. Final assessment will be the same as General Education students.



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