What should you do if the high power objective lens touches or breaks the coverslip

Answer : If this happens avoid using the high power objective lens, instead use other power lenses.

One should always use the compound microscope with great care. If the high power objective lens breaks the cover slip, it should be immediately informed to the teacher, professor, or any one who is authorized to handle this situation.

You can avoid this situation to occur by being extra careful, while using the high power objective lens adjust the lens using the fine knob adjustment.

Tell your teacher / instructor / professor.