Never touch thelenseswith your fingers. Your body produces an oil that smudges the glass. This oil can even etch the glass if left on too long. Use onlyLENS PAPERto clean the glass. Most educational labs want the microscopes to be covered and put back into the storage cabinet. Check with the head of the laboratory to verify if this microscope safety procedure is required. Some laboratories leave the microscopes out so it is best to double check.