Human: How do you correctly use a protractor? Assistant: 
To use a protractor correctly, start by aligning one of the straight sides of the protractor to the line you want to measure. After that, find the angle by lining up the midpoint of the protractor with the vertex of the angle. Then, read the angle off the circular scale of the protractor. Finally, make sure that you reset the protractor to 0 degrees before you finish.