This lab is designed to reinforce the concept of density. Using the water displacement method students have to identify, which year of pennies is denser pre-1982 pennies or post-1982 pennies. This lab is easy to set up. The required materials are water, 100-mL graduated cylinder, small plastic cup(optional), balance, pre-1982 pennies (25), post-1982 Pennies (25), metric ruler, pencil, graph paper and graphing calculator (optional). After completing the lab, student will perform data analyses on their experiment. Student will create a graph, calculate percent of error and answer follow up questions.