| Year | Session | Title | Moderator(s) |
| 1993 | S | Tropical Ecosystems of Costa Rica | Ellen Weiss |
| 1993 | F | The Nature of Our Universe | Carl Swanson |
| 1994 | S | Solutions for a Sustainable Planet | Joylane Hinkle |
| 1994 | F | Time to Choose (Ecology) | Joylane Hinkle |
| 2000 | F | Untangling Environmental Issues | Dorothy Rosenthal |
| 2002 | F | Golden Age of Astronomy | John Armstrog |
| 2004 | F | An Introduction to Meteorology | John Armstrong and Hal Stubbs |
| 2007 | F | Natural Disasters | John and Lise Armstrong |
| 2008 | S | Global Climate Change | Jim Harvey |
| 2010 | F | Volcanoes and the Human Experience | Jim Scott |
| 2010 | F | When the Well Runs Dry: Water in 21st Cent | Peter Ferber and Carol Jolly |
| 2011 | S | Global Warming/Climate Change: What does the Future Hold? | Joel Halpern and Gordon Wyse |
| 2011 | F | The Solar System: the Last 30 Years | Jim Scott |