Two-dimensional shapes - math grade 2 - lesson 41

1.TEACHER DO: Display large square, rectangle, triangle, and circle so all students can see.

TEACHER SAY: Last year, you were introduced to some shapes and some vocabulary words to describe them. Turn and Talk to your Shoulder Partner and tell them everything you remember about these shapes and the vocabulary words you used to describe them. Give me a Thumbs Up when you are ready to share your thinking.

STUDENTS DO: Turn and Talk to their Shoulder Partner about what they remember about shapes from last year. Give a Thumbs Up when they are ready. Selected students share with the whole group.

TEACHER SAY: Yes, last year you learned the names of these shapes and how many sides and corners they each have. Now that you are older, you are ready to use a new vocabulary word for corner. Say the word VERTEX with me.

STUDENTS DO: Say: vertex.

TEACHER SAY: One corner is called a VERTEX. When we are talking about more than one vertex we call them VERTICES. Say vertices with me.

STUDENTS DO: Say: vertices.

TEACHER SAY: Help me count the vertices in this square.

TEACHER DO: Point to each vertex as you and the students count aloud.

STUDENTS DO: Count the vertices aloud with the teacher.

TEACHER SAY: Great job. A square has 4 vertices. It also has 4 sides.

TEACHER DO: Point to each side of the square.

TEACHER SAY: Raise your hand if you know how many vertices a triangle has.

STUDENTS DO: Raise their hand to volunteer. Selected students share their answers.

TEACHER SAY: Wonderful. A triangle has 3 vertices. It also has 3 sides.

TEACHER DO: Point to each side of the triangle.

TEACHER SAY: Which one of these shapes does not have any vertices? Raise your hand when you know.

STUDENTS DO: Raise hands to volunteer. Selected students share their answers.

TEACHER SAY: Yes, the circle does not have any vertices. It does not have straight sides either. Good observation. All of these shapes are two-dimensional shapes. They are flat and have two dimensions—length and width.

2.TEACHER DO: Display the hexagon, pentagon, trapezium, and rhombus with the other shapes.

TEACHER SAY: This year, we have four more two-dimensional shapes to add to our collection.

TEACHER DO: Briefly point to and name the hexagon, pentagon, trapezium, and rhombus. Do not discuss the number of sides and vertices of the shapes at this time.

TEACHER SAY: Let’s talk about another important vocabulary word—ATTRIBUTES. ATTRIBUTES are features, or parts. When we talk about shapes, we usually talk about the number of sides or vertices. Sides and vertices are ATTRIBUTES of shapes. Four of the shapes up here have some attributes in common. I am going to give you 1 minute to look at the shapes to see if you can identify four shapes that share attributes.

STUDENTS DO: Analyze the shapes to determine which four shapes have common attributes.

TEACHER SAY: Turn to your Shoulder Partner. Discuss which four shapes have the same attributes and what those attributes are. Give me a Thumbs Up when you are ready.

STUDENTS DO: Share their thinking with their Shoulder Partner. Give a Thumbs Up when ready. Selected students share their observations.

TEACHER SAY: Yes. The square, rectangle, trapezium, and rhombus share attributes. They all have 4 sides and 4 vertices. All two-dimensional shapes with 4 sides and 4 vertices are called

QUADRILATERALS. That is a wonderful new Primary 2 math vocabulary word. Say quadrilaterals with me.

STUDENTS DO: Say: quadrilaterals.

3.TEACHER SAY: Let’s investigate these shapes more. In small groups, you are going to explore these shapes and identify their attributes. Take out your student book and turn to page Lesson 41: Apply.

STUDENTS DO: Take out the student book and turn to page Lesson 41: Apply.

TEACHER DO: Help students Count Off into groups of three.

TEACHER SAY: You will work with your group to identify and record the number of sides and vertices on each of these shapes. You may mark the shapes if you would like. Let me show you one way to do that.

TEACHER DO: Draw several kinds of triangles on the board as shown below:


TEACHER SAY: What are these shapes?

STUDENTS DO: Raise hand to answer. Selected students answer the question.

TEACHER SAY: Yes, these are triangles. How do you know?

STUDENTS DO: Raise hand to answer. Selected students share their thinking.

TEACHER SAY: Yes, each of these shapes has 3 sides and 3 vertices. But they do not all look the same. Any two-dimensional shape that has 3 sides and 3 vertices is a ______.

STUDENTS DO: Say: triangle.

TEACHER SAY: Now let me show you an easy way to investigate these shapes for attributes. We will do the triangle together. I am going to draw lines through each of the sides and circle the vertices.

TEACHER DO: Draw lines through each side and circle the vertices on each of the triangles as below:


TEACHER SAY: On page Lesson 41: Apply in your student book, you will see a chart with these same shapes. Once you and your group determine the number of sides and vertices for a shape, you will record your findings on the chart. You will also draw a star on all of the shapes that are quadrilaterals. You may begin.

STUDENTS DO: Investigate the shapes in the student book with their partners, record their findings, and identify the quadrilaterals.

TEACHER DO: Allow time for students to complete this activity. Walk around the room and offer help as needed.

TEACHER SAY: Let’s go over the chart together to be sure we all found the correct attributes for each shape.

TEACHER DO: Go over the attributes for each shape. For the quadrilaterals, briefly discuss the differences between their 4 sides (as noted below) to help students understand how they are different. Use the trapezium to help students understand the vocabulary word PARALLEL.

STUDENTS DO: Check their charts for correct information. Make corrections if necessary.

TEACHER SAY: Th at was a lot of hard work. You all did a great job filling in your charts and identifying the attributes of two-dimensional shapes.