The best microscope for your classroom will depend on the samples you wish to look at. In general, a compound microscope with an objective providing at least 100x magnification is required to see individual cells. For observing smaller cells or cellular components, a higher magnification is necessary. You will also want to consider the light source for your microscopes. Less expensive options will likely rely on a mirror which reflects ambient light in the room to illuminate the sample. This sort of microscope may be adequate if your classroom has access to large windows providing ample natural light. However, the ability to observe your sample may be affected by time of day, weather, and season. A direct light source will provide better and more consistent illumination, but will come with a heftier price tag. Additional microscope characteristics like cordless vs. corded, fine and coarse vs. single focus knob, and binocular or monocular eyepieces can be determined by the resources in your classroom, budget, and teacher preference.