13. Using a protractor:
Students have the following misconceptions when using a protractor:
A protractor must always be placed in the horizontal position, regardless of the
orientation of the angle being measured
When measuring angles always start from the right/left.
Students need to be introduced properly to the instrument and its features, as with other
instruments in mathematics. Proper use, and sufficient practice and formative assessment ensures
that they are familiar with the instrument. They must be reminded that:
The point where the perpendicular lines intersect at the centre base of the protractor must
be placed at the point at which the angle to be measured is located.
One of the arms of the angle to be measured must be aligned to the right or the left with
the horizontal line at the base of the protractor. The angle is measured by looking at the
graduations starting from zero.