In a typical onion cell lab, students observe the structure of onion cells using a microscope. Students usually complete the lab using both low-power and high-power magnification.
At the start of the lab, each student prepares a slide using a thin slice of the inner membrane of an onion. The specimen is placed on a slide, and a drop of water or stain is added. A cover slip is placed over the onion slice to prevent folding or wrinkling. The students examine the specimen under the microscope, making observations of cell size and shape, number of cells visible and any detectable cell structures.