Positives

• These graphs show how the extent of sea ice changes over a year due to the seasons and, more importantly, how the amount of sea ice, particularly in the Arctic, has decreased over time. 
• Students can click on the data lines to select a specific date, and the map below the graph will provide a visual depiction of the extent of sea ice on that date.
• Students can switch between Northern and Southern Hemispheres by clicking "switch hemispheres" in the top righthand corner of the screen.

Additional Prerequisites

• The link to the NCEP Climate Forecast System does not work.
• The different plot lines can be turned on and off by clicking the individual years below the graph.

Differentiation

• Math or science classes could have students calculate the percentage of change in sea ice extent between the same date in two different years. 
• Earth science classes could discuss what has caused the decrease in the amount of ice since the 1970s and what can be done to stop the damage.
• Other resources on this topic include this Vox video on what melting sea ice means for the Arctic, this lesson on the difference between land ice and sea ice, and this NASA lesson on sea ice and global warming.