Does Spring Journey North?
Mapping the Green Wave of Spring

Journey North uses tulips to indicate spring's arrival throughout the country. But here's a question to ponder:

"Does spring truly move northward?"

Map the Data
On your own Journey North Maps, use dots to add new tulip garden data each week showing where tulips have emerged and bloomed. Describe the pattern you begin to see.

• What direction(s) is spring moving? Does anything surprise you?
• How would you explain what you see?
• What do you think will happen next?

These isopleths (lines) show places with the same average temperatures on a certain date.

Newest gardens are circled

1. Imagine drawing the wave of spring at different stages over the next months as spring moves across the continent. A line like that is called an "isopleth." It is a line on a map connecting points where one variable has a constant value, such as a date. The other variable changes. (The example to the right shows places that have the same temperatures on a certain date.)
   
2. Using this spring's tulip data (reported in every Update), you can show how spring moves forward by showing how many tulips have emerged or bloomed by certain dates. Here's one way:
   
   a) Each Monday, circle all the tulip gardens that have emerged this week.
   b) Draw a line that more or less connects these dots.
   c) Repeat this, drawing a new line each week until the wave of spring has advanced across the entire region.
   
   Teacher Tip:
   Use a clear plastic/transparency overlay on top of your classroom map to draw the isopleth map. You can use another overlay for a second map that shows when tulips bloom throughout the country.

Journal Questions

• What patterns do you notice? How would you explain them?
• What general statement can you make?
• Did anything surprise you? What questions do you have?

Digging Deeper
Try to complete this statement:

"Spring advances at the average rate of XX miles per week."

Hint: To figure this out, measure the distances between the waves on your map. Then use the map's scale to figure out the actual distances. To get an average, add these up and divide the total miles by the number of lines you drew.

National Standards