What is a Triangle?

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Students will be able to name and describe the attributes of a triangle.

Big Idea

When a Line Bends...A Shape Begins is a great book to use to introduce 2-dimensional shapes. The students will be introduced to all of the basic 2-dimensional shapes and learn about the attributes of a triangle.

Problem of the Day

5 minutes

I start the lesson with a problem of the day to help students review skills and concepts from prior lessons and develop their ability to problem solve.  I call the students up to the carpet. The students find their spots while saying this chant with me.

Criss cross, applesauce, hands in your lap, eyes on the teacher, you've got to show me that.

I project the Problem of the Day on the SMART Board and say to students, "This is our Problem of the Day for today.  This says 'Line up. Tell who is before you in line. Tell who is after you in line.This Problem of the Day requires everyone to participate and answer."  I have all students line up.  My students have a line order that they always get in, so I have them get in that order to eliminate arguing where they are in line.  When all of the students are in line, I start with the first person and go down the line with each student saying "_____ is before me.  _______ is after me."  When the last student has answered.  I have the students return to the carpet.

I tell students, "Today we are going to start learning about shapes.  We are going to read a fun story and learn about triangles!"

Presentation of Lesson

25 minutes

I show students the book When a Line Bends...A Shape Begins by Rhonda Gowler Greene.  I tell students that in this story,  we will hear about a lot of shapes.  We are going to pay extra close attention to the section of the story about the triangle.  I read the story aloud.  When finished, I pull up this PowerPoint presentation from TeacherspayTeachers.com.  I show the first slide and ask, "What shape is this?"  (Triangle)  I trace over one of the sides.  "This is a side.  Each straight line that makes up a shape is called a side.  How many sides does a triangle have?"  (3)  I point to a corner.  "The place where two sides meet is called a corner.  How many corners does a triangle have?"(3)  I sing the Triangle Song.  I have the students sing with me the second time.

I tell students that we will continuing to practice on a Triangle worksheet.  I show students the paper and say, "We will be working on this paper together.  You need to get out a pencil and put your name on your paper.  When your name is on your paper hold your pencil in the air, that will let me know that you are ready to start."  I like to have students hold up their pencils or put their hands on their heads when they are finished with a task.  It makes it easy for me to see who is ready and also keeps the students from writing all over their papers while they wait for other students to finish.  I hand each student a paper for them to take back to their seats and while the students are writing their names, I turn on the projector and document camera and display the worksheet on the SMART Board.  When all students have their pencils up, I say, "At the top if the paper there are two triangles.  On the first triangle, the red is showing one side.  How many sides does the triangle have?"  (3)  "Let's write a 3 on the line.  On the second triangle, the red is showing one corner. How many corners does a triangle have?"  (3)  "Let's write a 3 on the line.  The directions on the next section of the paper say ‘ Name the shape.  Circle the matching shapes'  What is this shape?" ( A triangle)  "We need to circle the other triangles.  A triangle look several different ways, but as long as it has 3 sides and 3 corners, we know it is a triangle."  I call up a student to point to the triangles.  I repeat this with the next question.  "Flip your paper over.  On the back the directions say, 'Color the triangles.'  You may finish the paper on your own.  When you are finished,  put your papers into the paper tray in the front of the classroom and get your center."


20 minutes

Since the students finish their papers at different times, I circulate through the room to make sure that students are completing their papers, putting it in the tray and getting their centers.  This week's centers are:

Shape Monster Book (Hubbardscupboard.org)
My Shape Flip Book (KindergartenCrayons.blogspot.com)
Building Shapes (Teacher Made Resource, craft sticks, fruit loops, noodles and drinking straws )
Shapes - Lakeshore Instant Learning Center
Shapes Adventures SMART Board
- Lakeshore Interactive Activity

I quickly circulate to make sure students are engaged and do not have any questions about how to complete the centers.   I pull three groups during centers.  I pull the first group for 10 minutes and the other two groups for 5 minutes each.  The first group is comprised of the students who were having trouble identifying numbers and matching the numbers to objects.  Even though we are working on shapes, I start with identifying and matching numbers to objects for this group since they need to master this skill.  I have a basic idea of who I want in each group based on recent assessments, but I also take into account how the students did in the whole group lesson.  I pull the students back to my small group table to do a reteach activity using flash cards and manipulatives (for this lesson I used two color counters).  I show the flash cards and have students practice identifying the numbers.  I then give each student a pile of counters (1-10) and have them pick the number card that matches their group.  I then put some attribute blocks on the table and have each student choose a triangle.  I have the students run their finger along the side as we say side and count the three sides.  I have the students touch a corner as we say corner and count the three courners.  The next two groups of students do just the activity with triangles.  I do this much quicker for these groups.  Prior to clean up, I check in with each table to see how the centers are going.  I turn on Tidy Up by Dr. Jean.  Students clean up and return to their seats.


5 minutes

I close the lesson by having a student come to the board and draw a triangle.  I ask, "What shape is this?"  (A triangle)  "How many sides does it have?"  (3)   "How many corners does it have?"  (3 I mention positive things that I noticed during centers.  I also include something that needs to be better next time.  I review what we did during our whole group lesson.  "Today we learned about triangles.  Triangles are two-dimensional shapes with 3 sides and 3 corners.  Tomorrow, we are going to learn about another two-dimensional shape!"