Lesson Plan

Identify an angle as a geometric shape formed by two rays that share a common endpoint (vertex), and name angles using three-letter notation or by the vertex

Describe angle measurement as the amount of turning from one ray to the other, connecting this rotation to a fraction of a full circle centered at the vertex

Explain why one degree equals 1/360 of a full circle rotation and why an angle measuring n degrees turns through n one-degree angles

Classify angles as acute (less than 90 degrees), right (exactly 90 degrees), obtuse (between 90 degrees and 180 degrees), or straight (exactly 180 degrees), using a right angle as the benchmark

Demonstrate that the size of an angle depends on the amount of rotation between the rays, not on the length of the rays

4.MD.C.5

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: a. An angle is measured with reference to a circle with its center at the common endpoint of the rays, by considering the fraction of the circular arc between the points where the two rays intersect the circle. An angle that turns through 1/360 of a circle is called a "one-degree angle," and can be used to measure angles. b. An angle that turns through n one-degree angles is said to have an angle measure of n degrees.