For observing microorganisms in water samples collected from a pond, the most appropriate microscope for students to use would be a **compound light microscope**.
Compound light microscopes are well-suited for viewing small organisms, such as microorganisms, algae, and protozoa, in liquid samples like pond water. They are relatively easy to use and are commonly found in educational settings. Compound microscopes use visible light to illuminate the specimen and provide a 2-dimensional view of the microorganisms.
Electron microscopes, such as transmission electron microscopes (TEM) or scanning electron microscopes (SEM), offer higher magnification and resolution but are typically more complex and expensive, making them less suitable for a classroom or introductory laboratory setting.
So, a compound light microscope is the best choice for students to observe microorganisms in pond water samples.