Additional resources
If you or your students would like to explore the topic further, these additional resources will be useful.
Interactive simulation, Isotopes and Atomic Mass from PhET Simulations and An associated classroom activity, Isotopes and Atomic Mass - Guided Inquiry Activity, developed by Timothy Herzog
An article by Scientific American, How are past temperatures determined from an ice core?
A Classroom/Laboratory Activity from Columbia University, The Climate System course (taught by Peter Schlosser, Stephanie Pfirman, Mingfang Ting, Jason Smerdon) Laboratory Activity, Vostok Ice Core