eng Science and Education Publishing World Journal of Chemical Education 2375-1657 2016-06-18 4 2 45 48 10.12691/wjce-4-2-3 WJCE2016423 article Juan M. Sanchez juanma.sanchez@udg.edu 1 Department of Chemistry, University of Girona, 17003-Girona, Spain A simple and fast exercise is outlined to show science students the importance of determining the size of a sample and also the quantity of sample in order to minimize sampling error and improve accuracy, and to achieve a desired error. http://pubs.sciepub.com/wjce/4/2/3/wjce-4-2-3.pdf in the classroom analytical chemistry sampling active learning