explain the characteristic scienctist use when observing organisms and placing them in the six kingdoms

Classification of organisms is done while considering many factors such as:

Cell type - whether the organism is prokaryotic or eukaryotic

Cell structure - This includes both the presence and composition of the cell wall

Body type - whether the organism is multicellular or unicellular

Mode of nutrition - the method through which the organism achieves its nutritional requirement, by consuming other organisms (heterotroph) or making its own food (autotroph)