Throwing the Dice: Teaching the Hemocytometer

 

Tested Studies in Laboratory Teaching, 2011, Volume 32

Sarah Salm & Jessica Goldstein

Abstract

One of the concepts taught to our science students is the use of the hemocytometer. Students in Microbiology, Genetics, and Anatomy and Physiology classes use the hemocytometer in a variety of activities, from quantifying yeast cells to counting white blood cells. Students do not always understand that cells on a hemocytometer are in a three-dimensional volume. While they clearly see on the slide a two-dimensional square with measurable length and width, they do not perceive that use of the cover slip adds height, the third dimension. They also do not always grasp the concept that the number of cells counted on the hemocytometer represents only a fraction of the total number of cells in a milliliter and that the number determined by counting on the hemocytometer can be used to estimate the final cell count in a larger volume. In this workshop we present a short lab activity in which students use dice and rulers to understand the hemocytometer. We then present an activity in which students apply their newfound knowledge of the hemacytometer to quantify the number of chloroplasts and thus the amount of chlorophyll in spinach leaves.

Keywords:  chlorophyll, hemacytometer, chloroplast, cell counting, dice, spinach

Dalhousie University (2010)