Final answer:
Under a microscope, we can learn the shape, cell wall characteristics via Gram staining, and arrangement of bacteria, which aids in identifying the infection type and appropriate treatment.
Step-by-step explanation:
By examining bacteria under a microscope, we can learn several things about these microorganisms. First, we can determine the shape of the bacteria, which can range from cocci (spherical), bacilli (rod-shaped), to spirilla (spiral-shaped). Second, using various staining techniques such as Gram staining, we can learn about the characteristics of the bacteria's cell wall composition, which can classify them as either Gram-positive or Gram-negative. This is important because it influences the type of antibiotics that will be effective against the infection. Lastly, the arrangement of the bacteria (for example, in pairs, chains, or clusters) can provide additional clues to their identification and the nature of the infection.