Forming 2D shapes

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SWBAT compose new plane shapes from composite shapes.

Big Idea

It's like putting a puzzle together! This lesson will assist my students in describing geometric shapes by their attributes by combining them together to form other composite shapes.

Rev Them Up

5 minutes

To develop the foundations for understanding geometry, first graders need to practice how shapes can go together to create composite shapes. Also, they need to begin seeing shapes within an existing shape. The Common Core created this standard for students to develop skills in solving shape puzzles, creating designs with shapes, and completing and keeping a shape as a unit (1.G.A.2). Being able to manipulate shapes and test hypotheses of shifting them to build new shapes attributes to their ability to describe geometric attributes and determine how shapes are essentially alike and different. Students learn to examine the structure of a shape to determine its usage and placement within a larger shape. This helps them see how important the structure (e.g., vertices, edges, etc.) is for shapes to go together (MP7). 

I am going to give them playtime with geoboards to begin today's lesson. They love using these and I will encourage them to build shapes we have talked about by calling out the number of edges and vertices for different shapes, e.g. square, rectangle, hexagon, triangle, etc.

Whole Group Interaction

10 minutes

We will practice building plane shapes and then connect them to form new composite shapes. I will have my own Geoboard and model what I am asking them to do and gradually release them to completing tasks on their own.

Student lets build a small square using pegs that are right next to each other. Let's build another one right next this one and have them sharing two pegs. Let's build one on top of each of them and have them share pegs. Do you see 4 small squares that are touching each other? (Yes) What do you around the outside edges? (I see a large square and the little squares are inside the big one.) Did we build a large square from 4 little ones? (Yes)

Take everything off and let's make a small triangle. Make another one next to it, but upside down, now another one right side up and they should all be touching. Let's keep going and see if we can make a large triangle. How many more triangles did you have to add? (1) How many little triangles did you make altogether? (4) 

Can we make a rectangle out of several small triangles? (Students will be building shapes to try an complete the task.)

Independent Practice

10 minutes

My students love stations to go to during free time and for independent practice, so I set them up as often as possible. You can go here to print this great 2D shapes practice station. I printed them in color and pulled out baskets of shapes for them to use for each card.

Students will be rotating through the stations for independent practice. You can see they enjoyed the challenge of forming shapes. I will be walking around the room and checking on student progress during the rotation. Some of the practice stations will be challenge and I want to be on hand in case some needs me to offer some alternatives to flipping, moving, or sliding a shape to get it in place.


5 minutes

I will give each student 6 triangles of equal size and ask: What shapes can you create with these triangles?

I am hoping to see things like:

  • I made a square out of 2 triangles.
  • I made a rectangle out of all of them.
  • I made a trapezoid out of 4 triangles.

This will allow me to see how they are attempting to place shapes together to form two-dimensional shapes and check their understanding.