## Activity 1.4: Drawing a Trend Line (20 min)

Students discuss various strategies for how to identify trends in two examples of data sets: global temperature anomalies and Lake Superior ice cover.

### Materials You Provide

### Resources Provided

### Setup

Print one copy of the 1.4 Drawing a Trend Line Worksheet for each student.Prepare a computer and projector to display the presentation. Retrieve students’ completed worksheets from the previous activity with their graphs of arctic sea ice data.

### Directions

### Assessment

This activity contains numerous opportunities for formative assessment. First, see how students describe the global trend of temperature anomalies in step two. Next, see what explanations they provide when you ask them to predict how much arctic sea ice will be on Lake Superior in five years. Do they confidently make a prediction, or do they suggest that they cannot predict due to the variation in the graph? Finally, monitor how easily they are able to construct the trend line on the Lake Superior graph in step four. If they have trouble with either of these, you may want to revisit these steps before moving to the next Activity.

### Tips

- The method included in this activity represents just one of many ways to quickly find a trend in noisy data. If you have a preferred method you are more comfortable with, you might want to experiment with multiple methods in this activity.
- If students are having trouble identifying a trend in the data, have them calculate an average of the stars on the left side of the graph and the stars on the right side, and then draw a line going through the two new averages. This should make the negative trend very clear.

### Modifications

For more advanced math students, consider having them constructing the trend line from the scatter plot using point-slope form. This video includes a short tutorial: https://learnzillion.com/lessons/250-write-a-trend-line-from-a-scatter-plot and https://learnzillion.com/resources/51255

### Extending the Learning

Have students find data sets online that they can transform into scatter plots and then calculate the trend.