Combine More 2D Shapes

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SWBAT compose a new shape by combining two-dimensional shapes.

Big Idea

What shape will you make? Kids can get creative with making composite shapes as they continue to explore composing new 2D shapes using a composite shape in this lesson.

Activating Strategy

10 minutes

I begin this lesson by playing the “Shape Song”.  While the video is playing, I encourage students to draw a picture of the shape in the air.


After the song, I review 2D shapes (triangle, rhombus, hexagon, square, and rectangle).  

Teaching Strategies

15 minutes

I display the first slide of the Combine More 2D Shapes.ppt and read the problem to the class:

Use two shapes to fill the outline on the left. Then draw a line to show the two shapes.

I ask the students:

  • Which two shapes can you use? (a triangle and a square)

I then hand out the activating worksheet and instruct students to cut out the shapes on the second page and use them to make the new shape on the left.  Have children place both shapes correctly in the outline. Then guide children to draw a line along the square’s top side to show the square’s outline, or to draw a line along the bottom side of the triangle.  By allowing students to manipulate pattern blocks, they are learning to experiment with using models in math (MP4).

I ask the students:

  • How does your drawing show shapes in the outline? (The line I drew shows a triangle and a square in the outline.)

Then I continue by reading the following directions aloud.

Use three shapes to fill the outline on the right. Then draw lines to show the shapes.

I guide children to identify the rectangle, square, and triangle.

  • Does it matter where you put the rectangle and the square? (They have to fit in the outline, but it does not matter which side the shapes go on the bottom.)

I then call on a student to come to the board and demonstrate how they used 2 shapes to make the shape on the left and three shapes for the shape on the right.

I direct student’s attention to the next slide on the powerpoint point out that the two rectangles are the same size. I then have children describe how the two new shapes are alike and different.

I ask the students:

  • How many different ways can you combine the rectangles to make a new shape?

Independent Practice

30 minutes

 We then work through the next slide (slide 3) on the powerpoint, which also corresponds with the first few problems on their Combine More 2D Shapes_worksheet.docx.  Once students are comfortable with making new shapes, I release them to complete the worksheet independently.

One thing you might want to be on the lookout for is that some children may not understand that they need to turn smaller shapes to get the new shape.  When I notice this is the case, I provide those children with two quarter-circle cutouts. I have children first model the new shape. Then I have them turn the quarter-circles so that they match the two quarter-circles in the answer choices.


5 minutes

To close out the lesson, I instruct students to draw two shapes in their math journal. Then draw what they would look like if you put them together to make a new shape.