Printable protractor, actual size

How to print it at the right size

• Press Print, and in the print settings choose Actual size or Scale 100% (not "Fit to page").
• Print on card stock if you can; it makes a stiffer protractor.
• Check the scale with the ruler on the sheet: it should measure exactly 10 cm with a real ruler.
• Cut out the protractors. For a see-through one, print on a transparency sheet instead.

How to measure an angle with a protractor

• Put the center mark exactly on the vertex, the corner of the angle.
• Line up the baseline (0°) with one arm of the angle.
• Read where the other arm crosses the scale.
• Use the scale that starts at 0° on the arm you lined up: the black outer scale counts from the right, the red inner one from the left.
• Check the answer makes sense: an acute angle is less than 90°, an obtuse angle is between 90° and 180°.

Drawing an angle

Draw a straight line for the first arm and mark the vertex at one end. Put the protractor's center on the vertex with the baseline along the line, make a small dot at the angle you want on the right scale, then join the vertex to the dot with a ruler. For angles bigger than 180°, use the full-circle protractor, or draw 360° minus the angle and mark the reflex angle on the outside.