Dust mites are too small to see with the human eye, but can be seen at 20 times magnification with a microscope. You can easily calculate the total magnification of your microscope to see if it is strong enough to see the mite by multiplying the eyepiece magnification by the objective lens modification.
Prepare the slide
Put a drop of water on the slide.
Put a speck of dust on the water drop with a pair of tweezers.
Lower the glass cover slowly, taking care to keep out air bubbles.
Remove tweezers and close cover completely.
Blot excess moisture from slide with paper.
Using the Microscope
Make sure the microscope is level, and turn on the light source.
Rotate the disk below the microscope stage to adjust the diaphragm to its largest diameter allowing the greatest amount of light.
Turn the nosepiece to the lowest power.
Place the slide on the stage beneath the stage clips.
Adjust the slide to center the specimen.
Bring the slide into focus using the large coarse focus knob.
Adjust to the clearest image by adjusting the small fine focus knob and the diaphragm.