Isotopes of Pennies
http://www.sciencenetlinks.com/lessons.cfm?DocID=176

Science Netlinks, American Association for the Advancement of Science


This lab activity from Science Netlinks is designed to explain the weighted averages that are used in average atomic mass calculations. Students can be expected to learn that isotopes of an element have different masses; that isotopes are atoms of the same element that have different numbers of neutrons; and that atomic mass is the weighted average of the naturally occurring isotopes of an element.

This resource is referenced here:
Resource Type: Scientific Resources:Overview/Reference Work, Activities
Topics: Chemistry/Physics/Mathematics