## Reflection: Advanced Students Radian Measure Day 1 of 2 - Section 2: Investigation

As the groups began working, one of the students ask me if he could calculate the arc length instead of measuring.  I asked him what he meant. He said, "I can take the circumference, then determine the portion of the circumference the angle covers."  He elaborated on this definition by using the example of a 30 degree arc being is 30/360 of the entire circumference of the circle. I was pleased that he was able to apply his prior understanding to the task. I plan to have the student explain his idea to the class.

Another student realized that she could find the measure of an 180 degree arc by multiply the 90 degree arc by 2.  She continued this reasoning by saying I can add the 60 degree arc and the 90 degree arc to find the 150 degree arc.  She clearly understood the concept of measurement and she applied reasoning skills developed earlier in the curriculum.

Using a Formula

# Radian Measure Day 1 of 2

Unit 7: Trigonometry as a Real-Valued Functions
Lesson 2 of 13

## Big Idea: By finding the ratio of arc length to radius, students will understand that radian measure is a real number.

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Standards:
Subject(s):
Math, Measurement, radian measure, circles, ratios
55 minutes

### Katharine Sparks

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