# Three Dimensional Shapes

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## Objective

SWBAT extend their understanding of attributes to include 3D shapes.

#### Big Idea

While 3 Dimensional shapes are not mentioned specifically in the Common Core, they do include the term face which is more appropriate for 3D shape attributes.

## Warm Ups

10 minutes

Even though this is a geometry unit, I want to keep students current with math facts and equations. Today I give a 2 minute fact test. I have students at different levels depending on past performance with their fact tests. The idea is for all students to fluently know their addition and subtraction facts to 20 by the end of the year. I give periodic quizzes (about one every 2 weeks) to check on progress. I encourage the study of math facts as ongoing homework and during early arrival activities each day.

I hand out the paper which I generate from www.mathfactcafe.com, and ask students not to turn it over until I tell them to start. I remind them that they will find both addition and subtraction facts on the paper and must be watchful of what the problem is asking. They must make sense of the problems and persevere in solving them (MP1). The paper has 25 problems with the first 13 being addition, and the last 12 being subtraction. Each paper mixes facts for the numbers students have mastered, so if they have mastered adding 5 to a number, then the paper will have facts for 1,2,3,4 and 5.

I say go and give students 2 minutes to complete the paper. At the end of two minutes I ask them to put their pencil away and take out a marker (so they do not add on or correct the problems as if they had been done correctly at the beginning). I read off the problems for 1 paper and ask others to wait (they can draw on the back) until we do their paper. The students call out the answers and we correct the papers together. Students record the number they got right at the top of the paper. There are 3 different levels of paper and each one takes about 2 minutes to correct. I am hoping that listening to the facts read aloud will provide students with another source of fact review.

I remind students that their goal is to be able to do about 20 of the problems correctly by midyear, and all 25 by the end of the year. I remind them to practice math facts whenever they can.

When all papers are corrected, and students know how they have done, I collect the papers so I can record the scores, and then I ask students to clear off their desks, stand up and stretch and be ready to begin the next part of the lesson in 45 seconds.

## Teaching the Lesson

40 minutes

Today I will review/introduce 3Dimensional shapes to the students. I have a set of small 3D shapes that include cubes, pyramids, cones, rectangular prisms and spheres that I purchased from a school supply store. I put a variety of shapes on each table, making sure that I have at least one of each shape for each child at the table (I presort the shapes so I can quickly pass out the shapes to each table).

I start by holding up a piece of paper and a rectangular prism. I ask students to show me some of the similarities and differences between the 2 things I am holding. (I hope that they will notice edges, corners, sides as similar and faces, more edges, etc. as different.) These are all terms that we used when talking about 2D shapes. If no one notices that one is flat and one has more sides (or faces) I will ask a question such as, "do they both have the same number of faces? The same number of edges?.

I do a similar thing with a triangle and a triangular pyramid. I also hold up a circle and a sphere.

I hold up the 3D shapes and ask students what they are called? They may give the exact names or notice that they are 3D shapes so they may say, "they are 3D shapes" or they might say, "cube".

I explain to students that the shapes that are not flat are 3 dimensional shapes and have different names and some different attributes than the 2 dimensional or flat shapes.

I tell students that they will now try to find the shape that I describe and hold it up without talking.

I say "this shape has 6 faces that are all square. It has parallel line segments all around its edges and every face looks exactly the same." (cube)

I repeat it with other descriptions such as "this shape is made up of 1 square and 4 triangles. It has 5 faces. It has 5 vertices. (triangular prism)

I have students find the sphere, rectangular prism, and cone using similar descriptions.

When students are doing a good job identifying the shapes, I tell them that they will be making some shapes today using paper and scissors.

I have found templates (nets) for making paper shapes. These templates can easily be printed for students.

## Creating and Discussing Shapes

30 minutes

I have templates for a cube and a square prism. I ask students to find their scissors. I put small pieces of tape on each desk (or a tape dispenser for each table).

I hold up the cube template and ask if students know what the shape might build? I show students how to cut along the dark lines on the outside of the shape (being careful not to cut off the tabs on the edges of some pieces). Precision is important here (MP6) I pass one out to each student.

I tell them that before they cut, they should draw a quick face on each face of the cube. The students have fun drawing the faces and it reminds them that this part of the shape is called a face.

When the cube is cut, I ask for each student to write their name somewhere on the printed sides of the paper. I ask students to follow me as I fold the pieces together. I show students how to add the tape to keep the shape together.

I repeat the process with the triangular prism and the rectangular prism.

We end the lesson today by placing our shapes on the shelf to refer to in another lesson.