Shapes in Our World: Exploring Triangles and Circles

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Students will be able to identify characteristics of triangles and circles and identify real-world objects that are these shapes.

Big Idea

Students have fun exploring the world of shapes as they learn about triangles and circles.


10 minutes

For this lesson, I get the students excited about the content by listening to and participating in the Triangle Song by Have Fun Teaching on YouTube.  The students get to make triangles with the arms and hands and walk and more with this fun song. It is a great way to focus the students and burn off a little energy before the lesson.  After the song, my students take their SmartBoard spots to begin direct instruction.  

Direct Instruction

15 minutes

For this portion of the lesson, I use my SmartBoard.  If you have a Smartboard, the file Circles and Triangles can easily be downloaded and opened.  If you have a different type of interactive whiteboard, you can still use this lesson by opening the file in Smart Notebook Express.  There is also a pdf of the slides so you can recreate this part of the lesson.  

I gather my students in front of the Smartboard.  I have cards with each student's name printed on.  These cards are used for selecting who will come up to the SmartBoard.

I open the first slide (SmartBoard Slide 1) with the lesson objective written in "student friendly" terms.  There is a content objective and a language objective to help focus on vocabulary expansion for my English Learners (ELs) to be congruent with SIOP instructional techniques  I read these objectives aloud for my students.

Content Objective
I can identify the characteristics of circles and triangles and identify whether a shape is a circle or triangle.

Language Objective
I can tell a friend if a shape is a circle or a triangle.

 We progress then progress through the rest of the slides. 

Slide 2: This is a triangle.

Slide 3:  A triangle has three straight sides and three corners.  I point out the sides and corners for the students.  We do not use the term vertices at this point in time.  Many of my students do not even know what a corner is in relationship to their own world, so I do not want to complicate the lesson for these students. 

Slide 4:  Is this a triangle?  I gather answers for the students.  I am amazed that many students say "no" because it is not orientated the way the students generally see a triangleI explain to the students,  It has three sides and three corners so it must be a triangle.

Slide 5: Is this a triangle?  I again solicit answers from the students.  They agree it is not a triangle.  I reinforce why it isn't.  It does not have three straight sides and three corners.

Slide 6: This is a circle.

Slide 7: A circle is made up of one curved line. Every spot on the line is an EQUAL distance for the center. I explain to the students that no matter where I am around the outside edge of the circle, I am always the same distance from the center of the circle.  I use the colored lines on the circle to help them better understand this characteristic of circles.  

Slide 8:  Is this a circle?  The students immediately shout out, "It's an oval!"  I am happy they know what an oval is, but I want them to understand why it is not a circle.  I want them to use their academic language.  I talk them through the fact that different points on the circle are not the same distance from the center.  I actually draw lines on the oval to assist their understanding of this concept.  

Slide 9:  Let's sort some shapes!  I invite students to come up to the board and sort the shapes. I have them explain the rationale behind where they put each shape.  

Slide 10:  It is time for my students to practice using their academic language with Turn and Talk.  Each student has an assigned Turn and Talk partner.   I have them hold hands with their partner and raise their hands in the air so I can make sure that everyone has a partner.  After everyone has a partner, I say to them.  Look at each shape.  Which one is a triangle?  How do you know?  Some students figure out immediately that it is a trick question.  I stress to the students that I want them to come with WHY.  After it is obvious that everyone has had a chance to talk, I ask a student to share their answer with the class.  The student tells the class that both shapes are triangles.  I ask the student to explain why.  The student tells the class that there are three sides.  I repeat the student's answer.  Both of these shapes are triangles because they have three sides.  It does not matter which way the triangle is sitting.  I take my finger and I rotate the shapes on the Smartboard s the students can see that no matter which way I turn the shapes, they are still triangles.

The students take their seats at their tables to begin guided practice.   

Guided Practice

10 minutes

For this portion of the lesson, you will need the Circle and Triangle Real World Shape Sort.  I print the cards on a colored printer and laminate for durability.  I printed four sets of the cards, so there was one set for each table of students in my classroom. The cards should be cut apart.

I distribute each set of cards to the tables face down.  I pass the cards out around the table so each student gets at least two cards. I then place one set of the larger cards that are labeled circle and triangle at each table.  I say to the students, we are going to sort some things that we find in our word as circles and triangles.  You will go around the table and hold up just one of your shapes.  You will say what it is and what shape it is.  For example, if I have a picture of a car tire, I would say, "The tire is a circle".  Then place the shape next to the sign that has the circle on it and the next person goes.  I want everyone to say the sentence.  Don't just put your card down.  Keep going around the circle until all of the cards are laid down.

The students begin the activity.  I circulate around the room to make sure they are sorting the shapes correctly.  Because I want my English Language Learners to expand their vocabulary I make sure the students are saying the sentences that describes their shapes.  I assist students by naming objects they are not familiar with as well. 

I check the students sorted cards.  The students pick up the cards and we prepare for independent practice. 

Independent Practice and Informal Assessment

10 minutes

I pass the Circle and Triangle Sorting Activity out to the students and have them put their names on the top of their papers.  I then explain to the students, We will be sorting some objects by shape.  You will be deciding if the shapes are circles or triangles.  I want you to cut apart the shapes and place them on the correct sections of the paper.  Do not glue until you have raised your hand for me to check our paper. 

The students begin working as I move around the room, checking their work.  I make sure to check in with my English Language Learners and have them name the different objects that they are sorting.

I correct any mistakes that the students may have made.  After they have glued the objects down, I have them place the paper in their mailbox.