Lesson 10

Classifying Shapes

Est. Class Sessions: 2–3
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Mathematical Standards

4.MD.C
Geometric measurement: understand concepts of angle and measure angles. (4.MD.C.7)
4.G.A
Draw and identify lines and angles, and classify shapes by properties of their lines and angles. (4.G.A.1, 4.G.A.2)

Standards for Mathematical Practice

MP1.
Make sense of problems and persevere in solving them.
MP2.
Reason abstractly and quantitatively.
MP3.
Construct viable arguments and critique the reasoning of others.
MP5.
Use appropriate tools strategically.
MP6.
Attend to precision.

In Part 1, students participate in activities in which they analyze, describe, and classify triangles. In Part 2, they complete similar activities with polygons.

Content in this Lesson

  • Identifying acute, obtuse, and right angles in shapes [E2].
  • Identifying parallel and perpendicular lines in shapes [E4].
  • Describing and analyzing 2-dimensional shapes based on their properties (e.g., number and length of sides, number and size of angles, relationships between sides) [E5].
  • Classifying 2-dimensional shapes using their properties [E6].
  • Justifying conclusions using geometric properties [E10].
  • Estimating the size of an angle using 90° as a benchmark.
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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

envelope for storing Triangle Sort Cards
scissors
centimeter ruler
1 set of Power Polygons™ (Shapes A–O)

Materials for the Teacher

Display of Triangle Sort Cards 1 and 2 (Student Activity Book) Pages 371 and 373
Display of Sorting Polygons (Student Activity Book) Page 375
Unit 9 Assessment Record
Math Facts Class Record
Shape Finder class chart from Lesson 9
Geometry Word Charts for the following shapes from Lesson 9:

Parallelograms
Quadrilaterals
Hexagons
Trapezoids
Rhombuses
Rectangles

chart paper
2 sets of Power Polygons™ (Shapes A–O)

Materials Preparation

Power Polygons™. Organize the Power Polygons™ into sets of 15 Shapes A–O so that student pairs can work with two complete sets.

Triangle Sort Cards. Have students cut out the 14 triangles on the Triangle Sort Cards 1 and 2 pages in the Student Activity Book and store the cards in an envelope.

Make a display set of the Triangle Sort Cards for whole class discussion.

Geometry Word Charts. Prepare to add one or two sheets of chart paper to the Geometry Word Chart. Title the page “Squares.”

Assessment in this Lesson

Assessment Expectation Assessed

Shapes Quiz
Assessment Master with Feedback Box
Teacher Guide - digital
E4.
Draw and identify intersecting, perpendicular, and parallel lines.
E5.
Describe and analyze 2-dimensional shapes based on their properties (e.g., number and length of sides, number and size of angles, relationships between sides).
E6.
Classify 2-dimensional shapes using their properties.
E7.
Identify line (reflective) symmetry.
E8.
Identify congruent shapes.
E9.
Identify slides, flips, and turns of shapes.
E10.
Justify conclusions using geometric properties.

DPP Item BB
Angle Measures
Teacher Guide - digital
E1.
Use addition and subtraction to find unknown angles.

DPP Item CC
Division Facts Quiz: Square Numbers
Teacher Guide - digital
E13.
Demonstrate fluency with the division facts for the square numbers.