How to Build a Protractor

A picture helps the building process

Building something is a very fulfilling activity. You research, gather the necessary tools and supplies, and achieve the satisfaction of making something. Step-by-step instructions make the building easy.

Things You'll Need

• paper
• printer
• scissors
• cardboard
• glue
• pen
• ruler

Instructions

The Easy Way

1. Print an image of a protractor. The internet has many sources.

2. Glue the picture to cardboard or heavy paper. This gives it firmness and stability.

3. Put the paper under a thick book or some heavy object for thirty minutes to help the paper bond tightly to its backing.

4. Cut out the picture, trying to stay as close to the outside boundary as possible. This ensures accuracy of measurement. Your protractor is ready to go.

Reinventing the Wheel

1. Draw a circle. Draw a diameter horizontally, bisecting the circle in half. Draw another diameter, vertically. This will become the 90° mark on your protractor.

2. Cut out the semicircle. This is the outline of the protractor. Mark 0 at the right edge, and 180 at the left most corner. These are the degree markings. Write 90 at the straight line coming up from the base.

3. Measure and mark the midpoint with a clearly visible dot. You can even punch out a small hole if you like. This is the origin of the protractor.

4. Find an image of a protractor. Enlarge it and print it out. Trace a ten degree segment. You can use the first marking -- the one that goes from zero to ten degrees. Cut out this narrow wedge.

5. Place this wedge on the protractor so the narrow end is centered at the origin. Write 10 at the outer (semicircular) edge. This is the ten degree mark. Move the paper another ten degrees. You do that by aligning the paper with the ten degree mark at the outer edge. In other words each ten degree mark you make becomes the new base. Mark each point in increments of ten -- 10,20,30 and so on till you have travelled the semicircle. You have now marked 180 degrees in ten degree increments. Your protractor is complete.

References

• Math Aids: Protractor Image
• Michael Ossman: Large Protractor Template