# Day 51: What in the world is a radian?

Today in Precalculus, the activity was developing the concept of a radian as a means to measure an angle.  Yay for the Dollar store…got a whole bag of coffee filters and 2 packs of index cards for \$3 and I have enough for at least 2 years of 3 classes of the activity.  Quite a bargain.  You probably know the drill…it shows up on Pinterest all of the time.  I have done the really fancy activity, but have settled for the ease and efficiency of this approach.  We start by finding the center of the coffee filer (nice review of geometry and using efficient methods), then draw in the radius and label it.  Next, the kids measure their radius onto the index card…talk about measuring unusual units – radii today – with an unmarked ruler.  We then radius arc lengths around the coffee filter, etc., etc.  Just through the use of fractional parts of a circle, students begin to make connections between degree measurements and radian measurements…love, Love, LOVE this activity.  Since it is Veteran’s Day, and no school, tomorrow I sent them home with another unit circle asking them to re-create it with radian measurements, determine radian reference angles and determining once again the rectangular coordinates of the intersection points of the unit circle and the terminal side of a special angle.  Can’t wait to see how they make the connections.  How do you use manipulatives to develop concepts in your classroom?

Posted on November 10, 2014, in Uncategorized and tagged , , , . Bookmark the permalink. 1 Comment.