Graph the Data

Now you are ready to compare temperatures during the El Niño event in 1997-98 to the normal temperature ranges for your selected area. First you need to select all the rows you are going to graph. Hold down the Control (Win) key or the Command (Mac) key, while selecting each of the following rows with the mouse: (a) month labels, (b) 1997, (c) 1998, (d) Average + 1 Standard Deviation, and (e) Average -1 Standard Deviation.

Next, select the Chart Wizard button (or choose chart on the Insert Menu), and the Chart Wizard box will appear. Select the line graph with markers displayed at each data value. 

Follow the directions on the Chart Wizard to create your graph. The data from each row you selected should be plotted, using the Month label row for labeling the x-axis.

As you study the graph, look for areas where either of  the El Niño year lines extend beyond either the average +1 or average -1 Standard Deviation boundaries. Where the El Niño year line falls outside the one Standard Deviation boundaries, you can say that the El Niño temperatures for that month were warmer (or colder) than normal for the selected region.

Was there any change in weather pattern during El Niño years?

From analyzing your graph, do you think the El Niño event affected temperatures in your selected region?

Explain your reasoning. 

(NOTE: You may want to discuss with students the concept that the decision to use ±1 Standard Deviation as your typical temperature range is a value judgment — not a hard and fast rule. This realization can lead to an interesting discussion on tentativeness, subjectivity, and other aspects of the nature of science.) 

An expansion of this activity that explores El Niño's effects on precipitation may be found at The Impact of El Niño Pt. 2.