Introduction to Angles

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SWBAT identify the number of angles for a given two-dimensional shape.

Big Idea

Students learn about angles and identify the number of angles in 2D shapes.

Warm Up

10 minutes

We are going to review our 2D shapes by playing a quick game of "Who am I?".   

I divide students into pairs and give each  pair a deck of "Who am I?" cards (these have a list of attributes for a shape and the question "Who am I?".

One student holds up a card and reads it to their partner.  Their partner then explains what the shape is and defends their answer by describing shape attributes.

If students have not played this game before (my students have),  model how to play in front of the class for maximum impact.

I allow students to play the game for 5-7 minutes before bringing students back together for the introduction to new material.

Introduction to New Material

10 minutes

I start class by drawing a picture of a square on the board.

This square has four angles. 

 I write this definition on the board:

Angle: the place where two lines intersect or come together.

Show students a variety of other shapes (trapezoid, hexagon, parallelogram, etc.) and ask them how many angles each one has.

Show students a square (right angle), a trapezoid (acute angle), and a hexagon (obtuse angle).  Circle the appropriate angles.

Turn and talk:  How are these angles similar or different?

Students might say that the angle on the trapezoid is small and the angle on the hexagon is big.  They might say the angle on a square looks like an L.

We are going to learn some vocabulary to explain angles.

Then, I add to the angles anchor chart 

Right angle: A corner angle (Draw or paste pictures of a right angle).

Acute angle: An angle that is less than a right angle (Draw or paste pictures of shapes with acute angles)

Obtuse angle: An angle that is greater than a right angle (Draw or paste pictures of obtuse angles) .

As a check for understanding, I show students some pictures of shapes and have them explain why they think they are right, acute, or obtuse. 

Guided Practice

10 minutes

I start the guided practice by handing white boards and white board markers to every student. 

I give the following prompts and have students draw the shapes on their white boards.  After each prompt, I  have at least one student share why they drew their shape.

1)   Draw a shape that has four angles. (multiple correct answers: have students explain their answers!)

2)   Draw a shape that has zero angles

3)   Draw a shape that has three angles

4)   Draw a shape that has six angles

5)   Draw a shape that has acute angles

6)   Draw a shape that has at least one right angle

7)   Draw a shape that has at least one obtuse angle

Independent Practice

15 minutes

Independent practice is tiered based on understanding of this concept.  I determine groups based on performance during the guided practice and general geometrical understanding. 

Group A:  In need of intervention

Students works in partners to draw shapes according to their angles. 

Group B: Right on track!

Students work in partners to draw shapes according to their angles.  This group also has one practice work sheet about right, acute, and obtuse angles. 

During the independent practice, I circulate focusing most of my attention on my intervention group to support students as they draw their shapes and to check for understanding. 


5 minutes

After students have finished their independent practice, I bring them back together and go over a few of the questions, cold calling students to share and defend their answers.  This closing serves as a chance for me to check student understanding and gives students a chance to share their knowledge and gain confidence talking and thinking about angles.