Tri, Tri, Tri angle!

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SWBAT identify and describe a triangle by stating a triangle's attributes.

Big Idea

Kindergarteners love to identify shapes in their environment. In order effectively do that, they must be able to recognize different shapes by their specific attributes. In this lesson kindergartners learn about different types of triangles.

Daily Calendar & Counting Review

20 minutes

Each day we begin our math block with an interactive online calendar followed by counting songs and videos.

Calendar Time:

We do calendar on Starfall every afternoon.  This website has free reading and math resources for primary teachers. It also has a  “more” option that requires paying a yearly fee. The calendar use is free. A detailed description of Daily Calendar math is included in the resources.

Counting with online sources: Today we did counting practice to reinforce the counting skills. We watched two to three number recognition 0-10 videos (one to two minutes each) because some of my students students were still struggling with identifying numbers correctly in random order. We watched "Shawn the Train" and counted objects with him to refresh our memories on how to count objects to ten and to reinforce one to one counting. Since we have started the second quarter of the school year, we added to today's counting practice: counting to 20 forward and back, counting by tens to 100 and counting to 100 by ones to get a jump on our end of the year goals.

Direct Instruction

15 minutes

I begin the lesson by reviewing our shapes chart. We review the names and attributes of circles and squares. Then we seize the moment and move on to creating our large triangles poster.

Me (holding up a triangle die cut): What do we call this shape?

Students: Triangle!

Me: What KIND of shape is it?

Students: 2 dimensional flat plane! (see video for 2D hand signal).

Me: How do you know it's a 2 dimensional shape?

Student (I call on a random hand up): It's 2 dimensional because it's flat and can't move.

Me: Okay! It is a 2 dimensional flat plane and it is flat and can't move. (We discuss the real attributes of a 2 dimensional shape in a later lesson, -------- which compares 2D and 3D shapes). Now let's chunk the word triangle to see if we can figure out what it means. We all put our fist under our chins to feel the syllables in the word triangle. We say the word and count the number of syllables. I ask, "How many?" The kids shout out two! I write the word down on the chart paper and underline the the two syllables as I read them.

Me: What could TRI-ANGLE mean? Hmmm. There are TRIcycles, TRIceratops, and TRIangles. What might TRI mean?

Student (random pick from raised hands): A tricycle has three wheels.

Me: Yes it does! So what do you think TRI means?

Student: Maybe it means three

Me: Well, what makes this shape a triangle? What can you tell me about this shape? (I draw the shape on the chart paper.

Students (names randomly picked one at a time from popsicle sticks in a jar) are provided with the sentence stem, "The triangle has __________."

Student 1: The triangle has three points.

Me: What are those points called? (If student is unable to answer, I ask another student to "help" him or her. (I circle the points on the triangle.)

Student: The points are called corners (some say vertex - either is accepted)

Me: What else makes this shape a triangle? What else can you tell me about it?

Student 2: The triangle has three sides. (If the student doesn't use a complete sentence to answer, guide them into rephrasing their answer into a complete sentence using the sentence frame.)

Me: Awesome! A TRIangle has three corners and three sides (I number the sides of the triangle on the chart).

We then add the triangle to our shapes chart and filled in the the attributes portion of All Shapes Chart. I placed it in between the circle and the square because of the number of sides a triangle has.

Next we took a few minutes to compare triangles, circles and squares by their attributes. I was looking to see if the students could describe each of the shapes.

Management Tip: To call on students, I pull names on popsicle sticks that are housed in a plastic jar. This prevents me from sub-consciously choosing the same students repeatedly or calling on too many girls versus boys and vice versa.

Tracing Triangles

15 minutes

I provide the students with plastic triangles of different sizes and angles (Magnatiles and Attribute Blocks from Lakeshore Learning). They trace the triangles on blank copy paper to get a "feeling" for triangles. I invite them to trace random triangles, or use them to make a picture for my higher-level learners.

I then have them circle the angles of the triangles and number them on each triangle. I have them number the sides of each triangle. My higher level kids have the challenge of recognizing that when two triangles are touching, they share a side.

We gather on the floor and share our triangle projects with our talking partners.

Classroom Management Tip: T-P-S

Exit Ticket

5 minutes

With this Triangle Search exit ticket, I check to see if the kids can identify triangles and if they can number them. I don't expect them to independently draw the shape after the first session of direction instruction.

Once they complete the exit ticket, I separate the work into two piles: Meets and Needs. My Meets pile is made up of the students who satisfactorily complete the exit ticket (one or none errors). My Needs pile is made up the students who still additional instruction or a small group experience.


5 minutes

We spend a few minutes discussing what we learn about triangles.

One student brings up the fact that when she put two triangles together they make a square. Another student shares that when he put two triangles together they make a rectangle. A third shares that she put two small triangles together to make a large triangle. 

I have the students come up and share what they had created in their tracing pages and point out the square, the big triangle and the rectangle.

One student points out that the triangles that created the square and the rectangle are different, and demonstrate this using the blocks.

These observations tell me that these students may need additional extension activities as we investigate the rest of the shapes. I know from their thinking that they are advanced in geometric thinking compared to the rest of the class. Tangram pictures is a perfect extension activity. They will either play with real tangrams and a tangram picture book, or online at Tangram Puzzles for Kids by ABCya!