| Chapter 22 - The Milky Way | 9 | May 30, 2012 |
| Chapter 24 - Weather | 16 | May 15, 2012 |
| Chapter 17 - The Sun | 16 | May 3, 2012 |
| Chapter 22 - The Atmosphere | 17 | May 2, 2012 |
| Chapter 20 - Ocean Water | 12 | April 24, 2012 |
| Chapter 16 - Basic properties of stars | 14 | April 23, 2012 |
| Chapter 19 - The Ocean Basins | 10 | April 12, 2012 |
| Chapter 15 - Small Solar System Bodies | 20 | April 10, 2012 |
| Chapter 18 - Erosion by wind and waves | 12 | March 27, 2012 |
| Chapter 14 - Satellites | 10 | March 20, 2012 |
| Chapter 17 - Glaciers | 17 | March 20, 2012 |
| Chapter 16 | 10 | March 14, 2012 |
| Chapter 15 - River Systems | 15 | March 8, 2012 |
| Chapter 13 - Uranus, Neptune, and Pluto | 8 | February 27, 2012 |
| Chapter 14 - Weathering and Erosion | 19 | February 21, 2012 |
| Chapter 12 - Jupiter and Saturn | 10 | February 21, 2012 |
| Chapter 11 - Mars | 10 | February 2, 2012 |
| Chapter 13 - Volcanoes | 12 | February 1, 2012 |
| Chapter 8 - The Rock Record | 13 | January 18, 2012 |
| Chapter 12 - Earthquakes | 16 | January 18, 2012 |
| Chapter 10 - Mercury and Venus | 7 | January 18, 2012 |
| Chapter 11 - Deformation of the Crust | 11 | January 12, 2012 |
| Chapter 8 - The Earth | 32 | December 19, 2011 |
| Chapter 10 - Plate Tectonics | 15 | December 15, 2011 |
| Chapter 9 - A view of Earth's past | 10 | December 7, 2011 |
| Chapter 6 - Light and Telescopes | 36 | November 30, 2011 |
| Chapter 7 - Resources and Energy | 15 | November 16, 2011 |
| Chapter 5 - Gravity and Motion | 28 | November 14, 2011 |
| Chapter 5 - Minerals of Earth's Crust | 16 | October 20, 2011 |
| Chapter 3 - Ancient Astronomy | 6 | October 18, 2011 |