This mini-lesson features time-series graphs of mean salinity at the surface for the Arctic and Antarctic regions. A series of questions guides students in their analysis.

In this mini lesson, students use in-water profiles of historical ocean data to analyze how sea surface salinity varies with depth. 

What is the hydrosphere and why is it important?

Helping students build their understanding of Earth's spheres and how they are connected is difficult.  Review the graphics to help identify the parts of the Earth System and the processes that connect them at the local, regional, and global scales.

This graphic organizer may be used to help students analyze the processes and components of Earth System phenomena.

This investigation is part of the NASA: Mission Geography Module "What are the causes and consequences of climate change?" that guides students through explorations in climatic variability and evidence for global climate change.