I have included a couple of pictures in this post to show how easy it is for kids to practice measuring angles by turns and also that the size of the rays of the angles are not important. These examples are some of those, "Ah, the light bulb just went off" moments that teachers live for...that make us want to come back in the next day and do it again!
The first hands-on picture helps my students see the 4 main rotations or turns of angles on a circle and what these turns look like. (90, 180, 270, and 360 degrees) This inexpensive manipulative consists of 2 styrofoam plates. I used a red marker on one plate. Students simply make a mid-point on both plates and cut one slit from the edge of the plate to the center. The plates can then be attached and rotated to make any degree of angles.
Styrofoam Plates and a Marker
The next two pictures are real eye-opening experiences. Besides the styrofoam plates, I make copies of smaller circles. I make white and yellow circles but the color doesn't matter at all. The procedures for prepping the paper circles are the same as for the styrofoam plates. When the kids measure angles with both set of circles they sometimes have a hard time believing that the angles measure the same even though the circles are such different sizes. My kids measure other items such as pattern blocks to reinforce the fact that, for example, a 90 degree angle is a 90 degree no matter how large or small the object.
Once the manipulatives are made, why not store them for future years? Saving the circles for future years saves precious time, copy paper, and $ for the plates.
As you can probably tell, my red styrofoam plates have been around for several years!
Now add a Smaller Set of Circles: Copy Paper
Another great way to reinforce this lesson is to take two strips of paper and fasten these with a brad. Let your students measure angles such as the corners of the walls and a pattern block square. It is exciting to watch as the kids realize that the size of the items doesn't make a difference in the angles!