About This Lesson
This lesson should be taught after students have developed a basic understanding of pH and ocean acidification. It works
especially well after the NOAA Ocean and Coastal Acidification Unit or after lessons such as Ocean Acidification: pH and
the Ocean's Balance, Making a Rainbow of pH, or LEGO Calcification Challenge.
Students will investigate how calcium carbonate responds to liquids with different pH values by observing pieces of eggshell
placed in several solutions. Because eggshells contain calcium carbonate, they provide a convenient classroom model for
investigating how acidic conditions can affect calcium-carbonate structures.
The acidic solutions used during this experiment are much more acidic than ocean water and are intended to accelerate the
reaction so students can observe changes during a classroom investigation. The activity should not be interpreted to mean
that shells in the ocean dissolve as rapidly as eggshells placed in vinegar.
