With a carload of cups, straws, seawater, red cabbage juice, bleach, lemon juice, seashells, yeast packets, and other miscellaneous items, I drove to the Cape Cod Sea Camps in Brewster, MA on a rainy day in mid-October to teach 36 7th graders from the Saint David’s School in NYC about ocean acidification. The inquisitive students proved to be quick studies and great sports, as they performed various experiments that demonstrated the concepts of pH and ocean acidification. We started with a brief presentation and Q&A session on ocean acidification and then broke into smaller groups that visited different “stations” around the room. At the “pH Demonstration” station, students used red cabbage juice, a natural pH indicator, to compare the pH of seawater with that of different household solutions such as bleach, vinegar, seltzer water, and lemon juice. At the “Ocean Acidification in a Cup” station, students used straws to bubble their exhaled CO2 into seawater and freshwater samples containing red cabbage juice pH indicator, watching the pH change right before their eyes. The “Yeast Experiment” station provided yet another opportunity to simulate ocean acidification. The students activated the yeast with warm water and sugar. Half of the group used a CO2 probe to directly monitor the CO2 being given off by the organisms, and the other half bubbled that CO2 gas into water and used a pH probe to monitor changes in the water pH. At the “Biological Impacts” station, students compared mollusk shells that had been soaked in just seawater (control) vs. acidified seawater. They looked at the shells under a microscope and also made observations of shell texture and brittleness. Students determined how many heavy books it took to break the control vs. acidified shells.
Materials and experiments were modified from the OCB ocean acidification lab kit and the C-MORE ocean acidification kit, which is available in the OCB Project Office for local teacher use.
Heather Benway, OCB Newsletter, Fall 2011. pp 20. Newsletter and full article.
