The document provides instructions for preparing onion cell and cheek cell slides under a microscope. To prepare an onion cell slide, a thin layer of onion is placed on a microscope slide and stained with iodine solution before adding a coverslip. For a cheek cell slide, cells are collected from the inside of the mouth using a cotton swab, smeared onto a slide, and stained with methylene blue solution before viewing. Both staining methods make cell features more visible under the microscope.