Benchmark Instructional Guide
Connecting Benchmarks/Horizontal Alignment
Terms from the K-12 Glossary
- Acute Angle
- Obtuse Angle
- Reflex Angle
- Right Angle
- Straight Angle
Purpose and Instructional Strategies
The purpose of this benchmark is to begin the understanding of angles and how they can be identified in lines and shapes. Understanding angles will be used to define shapes by their attributes. This builds on the work students completed in grade 3 to identify perpendicular lines in shapes in mathematical and real-world situations (MA.3.GR.1.1
- During instruction, students should gain experience using benchmark angles of 90° and 180° (MTR.6.1). For right angles (90°) students can use the corner of a piece of paper. By lining the edge of the corner of the paper on one ray to the vertex of the angle, students can determine that angles that are smaller than the corner are acute and angles that are larger than the corner are obtuse. Similarly, students can use the side of a piece of paper to determine if the angles are greater than 180°. Students believe a wide angle with short sides may seem smaller than a narrow angle with long sides. Students can compare two angles by tracing one and placing it over the other. Students will then realize that the length of the sides does not determine whether one angle is larger or smaller than another angle. The measure of the angle does not change.
Common Misconceptions or Errors
- Students believe a wide angle with short sides may seem smaller than a narrow angle with long sides. Students can compare two angles by tracing one and placing it over the other. Students will then realize that the length of the sides does not determine whether one angle is larger or smaller than another angle. The measure of the angle does not change.
Strategies to Support Tiered Instruction
- Instruction includes providing a graphic organizer and several examples of each type of angle (acute, right, obtuse, straight and reflex). The graphic organizer will have angles labeled on them for the students to use to help them classify the figures provided.
- For example, the teacher provides a graphic organizer similar to the one shown below. Along with the graphic organizer, the teacher provides examples of various angles to classify.
- Instruction includes providing a right angle and a straight angle printed on a clear transparency or sheet protector. Students lay the angles over angle examples provided by the teacher to help them classify the angles as less than 90 degrees (acute angle), greater than 90 degrees (obtuse angle), exactly 90 degrees (right angle), exactly 180 degrees (straight angle), or greater than 180 degrees (reflex angle). Students trace one angle and place it over the other to compare them.
- For example, the teacher may provide the student with a clear transparency with a right angle printed on it. The teacher provides sample angles and asks students to place the transparency over the angles. The students sort the angles into greater than 90 degrees, less than 90 degrees, and equal to 90 degrees. The teacher will then provide a straight angle printed on a transparency and have students use that to classify the angles that were sorted as greater than 90 degrees into an additional grouping. Students will determine if the angles are equal to 180 degrees or greater than 180 degrees.
Instructional Task 1 (MTR.4.1)
Part A: Draw and label an example of 3 objects that have a right angle.
Part B: Draw and label and example of 3 objects that have an acute angle.
Part C: Draw and label an example of 3 objects that have an obtuse angle.
Part D: Is it possible to find an object with a reflex angle? Why or why not?
Instructional Item 1
Which statement correctly describes the figure?
*The strategies, tasks and items included in the B1G-M are examples and should not be considered comprehensive.