In this unit, students develop their spatial reasoning skills by using a wide variety of attributes to talk about twodimensional shapes. Students analyze plane figures based on angle measurement and parallel and perpendicular lines. This unit extends prior knowledge of classifying twodimensional figures based on attributes and applies it to classifying triangles based on angle types. Students are likely to struggle with the various orientations in representing triangles, perpendicular lines, and parallel lines, and learning to mentally rotate to perceive them more clearly.
Key Concepts:
 Two lines are parallel if they if they are on the same plane and will never intersect, and perpendicular if they are on the same plane and intersect at a 90 degree angle (Lesson 1).
 Angle measurement is additive, and angle measures can therefore be added and subtracted (Lesson 4).
 Triangles can be categorized based on their angle types (Lesson 7).
 Patterns may have features that are not explicit in the rule of the pattern (Lesson 9).
Prior Knowledge Needed:
 Understand that shapes in different categories may share attributes (Grade 3, Unit 13; 3.G.1)
 Points, lines, line segments, and rays have specific properties (Grade 4, Unit 10; 4.G.A.1)
Units on the Horizon:
 Classifying twodimensional geometric figures; (Grade 5, Unit 11, 5.G.B.4)
 Geometric Constructions; (Grade 7, Unit 14, 7.G.B.5)
Lessons

Lesson objective: Understand lines can be classified as parallel and perpendicular. Students bring prior knowledge of lines and angles from 4.G.A.1. This prior knowledge is extended to identify and draw parallel and perpendicular lines as students class...

Lesson objective: Identify and differentiate between parallel and perpendicular lines. This lesson helps to build procedural skills with identifying parallel and perpendicular lines. A square corner is used here to identify right angles because it highl...

Lesson objective: Apply knowledge of parallel and perpendicular lines to design a playground. This lesson provides an opportunity for students to apply their knowledge and understanding of parallel and perpendicular lines to a reallife situation. Stude...

Lesson objective: Understand that angles can be composed and decomposed. Students bring prior knowledge of angles from 4.G.A.1. This prior knowledge is extended to additive angle measurements as students compose and decompose angles. A conceptual challe...

Lesson objective: Compose and decompose angles. This lesson helps to build fluency with composing and decomposing angles. Pattern blocks are used here because it highlights the composition of a cirlce with multiple angles. This work develops students' u...

Lesson objective: Solve problems with unknown angle measurements using addition and subtraction. This lesson provides an opportunity for students to apply their knowledge and understanding of angles to a reallife situation. Students are asked to determ...

Lesson objective: Understand that triangles can be classified based on the angle measurements and identify triangles as acute, right, or obtuse triangles. Students bring prior knowledge of angles from 4.MD.C.5. This prior knowledge is extended to classi...

Lesson objective: Divide twodimensional figures in half using a line of symmetry. This lesson helps to build fluency with finding lines of symmetry in twodimensional fugures. Mirrors are used here because it highlights that a line of symmetry creates ...

Lesson objective: Extend understanding of patterns that include given rules. Students bring prior knowledge of patterns from 3.OA.D.9. This prior knowledge is extended to patterns that follow a given rule as students solve the rule and use it to problem...

Lesson objective: Apply the use of patterns that follow a rule. This lesson provides an opportunity for students to apply their knowledge and understanding of patterns that follow a rule to a reallife situation. Students are asked to determine if there...