This is a sequence of 5 classroom activities focusing on the El NiÃo climate variability. The activities increase in complexity and student-directedness. The focus of the activities is on accessing and manipulating real data to help students understand El NiÃo as an interaction of Earth systems.

In this activity, students work in groups, plotting carbon dioxide concentrations over time on overheads and estimating the rate of change over five years. Stacked together, the overheads for the whole class show an increase on carbon dioxide over five years and annual variation driven by photosynthesis. This exercise enables students to practice basic quantitative skills and understand how important sampling intervals can be when studying changes over time. A goal is to see how small sample size may give incomplete picture of data.

In this activity students work with real datasets to investigate a real situation regarding disappearing Arctic sea ice. The case study has students working side-by-side with a scientist from the National Snow and Ice Data Center and an Inuit community in Manitoba.

This is an interactive graph that involves records of ice cover in two Wisconsin lakes - Lake Mendota and Lake Monona - from 1855-2010.

This interactive map allows students to experiment with decadal average temperature projections. Overall temperatures are expected to rise throughout the century and this tool demonstrates those projected measurements.

In this activity, students are introduced to tree rings by examining a cross section of a tree, also known as a 'tree cookie.' They discover how tree age can be determined by studying the rings and how ring thickness can be used to deduce times of optimal growing conditions. Next, they investigate simulated tree rings applying the scientific method to explore how climatic conditions varied over time.

This video from ClimateCentral looks at the way climate conditions can affect vegetation in the West, and what influence this has on wildfires. Drought and rainfall can have very different wildfire outcomes, depending on vegetation type, extent, and location.

In this intermediate Excel activity, students import US Historical Climate Network mean temperature data into Excel from a station of their choice. They are then guided through the activity on how to use Excel for statistical calculations, graphing, and linear trend estimates. The activity assumes some familiarity with Excel and graphing in Excel.

This short video, adapted from NOVA, explains how Earth's position relative to the Sun might be responsible for the dramatic shift in the climate of what is now the Saharan nation of Djibouti.

This is a video that documents the reflections of members of the Steger International Polar Expedition team reunited at the 25th anniversary of their landmark trek to the Arctic, and how climate change has made their trek difficult to replicate.