Missing Angles

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SWBAT solve for missing angle measures.

Big Idea

Students use known measures of complementary, supplementary, and right angles to find the measure of an unknown angle.


5 minutes

As students enter the room, they take out their Problem of the Day (POD) sheet and begin to work on the question on the SMART Board. The POD allows students to use MP3 in the discussions we have about the problem each day. 

To start class, I use students’ responses to the exit ticket from the previous lesson, Angles Everywhere. At the end of that lesson, students identified at least three examples of complementary and supplementary angles that they see in the real world, outside of the classroom. I make a list of all the examples that were generated and share the list with the class. We use the list to have a discussion about places and situations where angles can be seen, and help students generate a list for future reference.


30 minutes

The activity today requires students to call on their knowledge and understanding of the different types of angles we have covered in this unit. To complete the activity sheet, students need to know the sum of angle measures in a triangle, and be able to recognize complementary angles, supplementary angles, right angles, and other concepts covered.

Students work individually to complete the activity sheet. Once it is completed, I have students find a partner. Together, students compare answers and discuss their work. During their discussion, I ask students to identify the strategies they used to find the missing angles. I ask questions like, “Where did you start?” “What steps did you take?” “Were there any places where you got stuck?”


5 minutes

I use an exit ticket to wrap up the class. Here, students to identify a way to find a missing angle measure that they thought was helpful to discuss with their partner. I collect several strategies that we can discuss as a class, looking for any interesting discussion points or methods that stand out from the others. I do not want students to believe there is only one way to find a missing angle measure, especially if they are still unsure how to approach these kinds of problems. This exit ticket will generate strategies that students can use as we finish the unit.