Lesson 2

Tangrams

Est. Class Sessions: 2–3
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Mathematical Standards

3.G.A
Reason with shapes and their attributes. (3.G.A.1, 3.G.A.2)
3.MD.C
Geometric measurement: understand concepts of area and relate area to multiplication and to addition. (3.MD.C.6, 3.MD.C.7)
3.MD.D
Geometric measurement: recognize perimeter. (3.MD.D.8)

Standards for Mathematical Practice

MP1.
Make sense of problems and persevere in solving them.
MP2.
Reason quantitatively.
MP5.
Use appropriate tools strategically.
MP7.
Look for and make sense of structure.

Students sort the seven tangram pieces, and the class discusses how some of the sorts are alike or different. They find the area of each of the seven tangram pieces using a square-inch grid. Students make squares of different sizes using one, two, three, four, and all seven of the tans. They use a different method to verify the area of shapes.

Content in this Lesson

  • Developing spatial visualization skills.
  • Describing and analyzing properties of two-dimensional shapes [E1].
  • Measuring area of two-dimensional shapes [E10].
  • Finding a strategy for measuring area [MPE2].
  • Showing work [MPE5].
  • Using labels (e.g., square inches) [MPE6].
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Materials for Students

Daily Practice and Problems Lesson Homework Assessment

Student Books

 Student Guide  
Student Activity Book  

Teacher Resources

 Teacher Guide - digital  

Supplies for Students

set of tangram pieces
drawing paper

Materials for the Teacher

Display of first Tangrams page (Student Guide) Page 303
Display of first Area of Tans page (Student Activity Book) Page 421
Unit 11 Assessment Record
book of tangrams, optional
display set of tangram pieces
chart paper

Materials Preparation

Gather or Copy Sets of Tangrams. Each student needs one set of tangram pieces based on a 4-inch square. The longest side of the largest triangle is 4 inches. You can also make copies of the Tangram Set Master on heavy card stock or tag board. Make sets on different colors to make sorting and storage easier. Tangram pieces should be cut apart carefully on the dotted lines to ensure accuracy. If pieces do not fit the puzzles exactly, tell students that tangram pieces must fit inside or just outside the lines rather than on the lines of the puzzle.

Locate a Book about Tangrams. There are many resources that have tangram puzzles. Gather and be prepared to share a variety of puzzles to raise student's interest as they are introduced to these puzzles.

Create a Chart. Make a chart on chart paper as in Figure 1. Label it “Area of Tangram Pieces.” You will record the area of all seven tans on the chart as students measure them.

Figure 1
Figure 1: Chart to record tans' areas

Assessment in this Lesson

Assessment Expectation Assessed Math Practices Expectation Assessed

Tangram Sort
Student Activity Book
Page 419
E1.
Describe and analyze two-dimensional shapes using their properties (e.g., number of sides, length of sides, vertices, number and size of angles, number of right angles, and relationships between sides).
  

Find the Area
with Feedback Box
Teacher Guide - digital
E10.
Measure the area and perimeter of two-dimensional shapes.
MPE2.
Find a strategy. I choose good tools and an efficient strategy for solving the problem.
MPE5.
Show my work. I show or tell how I arrived at my answer so someone else can understand my thinking.
MPE6.
Use labels. I use labels to show what numbers mean.