Shapes and Angles

Lesson 6

Math

Unit 8

4th Grade

Lesson 6 of 18

Objective


Understand that an angle that turns through $${{1\over360}}$$ of a circle is called a “one-degree angle” and can be used to measure angles. Use a makeshift protractor to measure benchmark angles.

Common Core Standards


Core Standards

  • 4.MD.C.5 — Recognize angles as geometric shapes that are formed wherever two rays share a common endpoint, and understand concepts of angle measurement:
  • 4.MD.C.6 — Measure angles in whole-number degrees using a protractor. Sketch angles of specified measure.

Criteria for Success


  1. Understand that the unit of measure for angles is a degree, which is the measure of $$\frac{1}{360}$$ of a turn of a circle, and that all angles are measured with iterations of this unit.
  2. Understand that the degree measure of angles can be measured using a tool called a protractor.
  3. Measure benchmark angles with a paper protractor made up of 30° or 45° angles.
  4. Start to internalize benchmark angles, both what they visually look like and what their degree measure is (right angle, 30° angle, 45° angle, etc.) (MP.2).

Tips for Teachers


  • To help students build their visual models of benchmark fractions, you can use the applet Estimating Angles by NRICH. You can play as a whole class when there are a few minutes to spare, have individual students play online during class or a fluency/centers block, or refer parents to the website. 

Lesson Materials

  • Wedge (1 per student) — These were constructed in Lesson 5 using paper circles
  • Paper circle (1 per student)
  • Circular protractor (1 per teacher)
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Anchor Tasks

25-30 minutes


Problem 1

a.   What is the measure, in wedges, of the following angle?

b.   A ray that turns all the way around its endpoint and back to its starting place has made a full turn. We say that the ray has turned 360 degrees, often written 360°.

How many degrees has the ray turned from where it started?

Guiding Questions

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Student Response

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References

Illustrative Mathematics Grade 4 Unit 7 Lesson 8 Activity 1

Grade 4 Unit 7 Lesson 8 Activity 1, accessed on Oct. 13, 2023, 3:24 a.m., is licensed by Illustrative Mathematics under either the CC BY 4.0 or CC BY-NC-SA 4.0. For further information, contact Illustrative Mathematics.

Modified by Fishtank Learning, Inc.

Problem 2

a.   Determine how many degrees the wedge created in Lesson 5 measures, and use that to create a makeshift protractor to measure benchmark angles.

b.   Use a similar process to create a makeshift protractor that measures in increments of 45°.

Guiding Questions

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Student Response

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Problem 3

Using the makeshift protractors you made in Anchor Task #2, find the measure, in degrees, of each of the following angles. If an angle can’t be measured precisely with either protractor, make an estimate. 

a.   

b.   

c.   

d.   

Guiding Questions

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Student Response

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Problem Set

15-20 minutes


Discussion of Problem Set

  • A full turn is 360°. What could you do to find the degree measure of an angle that takes 10 turns to make a whole turn?
  • Shade in the region of a 45° angle on your eighths circle. What fraction of the whole turn is that? Do the same for your 30° angle.
  • What if you shaded in a region defined by a 120° angle on your twelfths circle? What fraction of the whole circle is that?
  • Use your protractor to explain to your partner what a degree is.
  • Use your protractor to trace some benchmark angles.
  • If you didn’t have a protractor, how could you create one?

Target Task

5-10 minutes


Problem 1

What fraction of a complete turn through a circle is 1°? 

Student Response

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Problem 2

What is the measure, in degrees, of a right angle? 

Student Response

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Problem 3

List the measurements, in degrees, of three benchmark angles. 

Student Response

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Additional Practice


The Extra Practice Problems can be used as additional practice for homework, during an intervention block, etc. Daily Word Problems and Fluency Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.

Word Problems and Fluency Activities

Word Problems and Fluency Activities

Help students strengthen their application and fluency skills with daily word problem practice and content-aligned fluency activities.

Next

Measure angles that are less than 180° using a 180° protractor. Distinguish angle measure from other attributes.

Lesson 7
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Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Lines and Angles

Topic B: Measures of Angles

Topic C: Measures of Adjacent Angles

Topic D: Shapes and Lines of Symmetry

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