When creating biological diagrams, it is important to consider three values: SAS, DS, DrMag.
SAS is specimen actual size, usually denoted in micrometers or millimeters.
DS is drawing size, namely the size drawn.
DrMag is drawing magnification. Think of this as a form of scale. When drawing large objects, the subject is scaled down and conversely, scaled up for lil' critters.
Assignment
Watch the Lesson on Microscope Calculations.
Complete the Magnification Assignment