When I moved from middle school science to high school science, one of the most surprising things I encountered was how much my high school students enjoyed coloring. Now obviously, science is more than an art project. [And along those lines, as Steven L. Pruitt mentioned, “If you can eat it, it’s probably not a model.”]
That said, when I was trying to figure out a way for students to explore the age of Earth’s crustal rocks during my unit on Earth’s geologic history, coloring wasn’t too bad of an idea.
The intention of the standard is for students to evaluate and use evidence, as well as the theory of plate tectonics, to explain patterns (hello, Crosscutting Concept!) in the ages of Earth’s crustal rocks. Well, before they could really get into looking at any sort of evidence or even the theory of plate tectonics, I wanted students to see the patterns they were going to be explaining.
Exploring Age of Crustal Rocks
I figured I had two options — I could simply present my students with a map, color-coded to identify the ages of oceanic crust, or I could somehow engage them in an activity where they discover those ages themselves. The first option seemed kind of boring (although that’s not to say I don’t use data with my students! It’s definitely one of my go-to Science and Engineering Practices!). Even so, I wanted to do more than just give my students a map, so I decided on the second option. That said, I quickly realized it would be very time consuming for students to plot the age of Earth’s crustal rocks on a large enough scale to complete a global map. While that, admittedly, would have been perhaps a better representation of collecting data, it just wasn’t feasible in my classes with my curricular requirements. Instead, I put together a simplified version where I provided the outline and a “color by number” approach to “collect” the relevant data.
Students colored their maps, following the key provided, and then they analyzed their maps to first identify patterns and then make sense of the patterns they found. Because I had marked the location of mid-ocean ridges, and they could obviously see where the continents sat, they were able to connect the formation of new rocks at the ridges and the disappearance of “old” rocks where ocean crust met the continents. Eventually, students discovered these “old” rocks were recycled back into the crust by subduction at the ocean-continent convergent boundaries, but at this point in the game, we were just focusing on patterns in the age of the crust.
After maps were finished, we debriefed together during the first part of our Explain phase. We used the “What I See, What It Means” analysis method to identify patterns we saw and interpret those to figure out what they meant. Through the discussion, students concluded:
- new rocks are formed by mid-ocean ridges
- the rocks get older as they move away from the ridge, indicating the crust is moving (hey, plate tectonic theory!)
- the oldest rocks could be found near the edges of the continents
We were on our way to meeting our standard! If this is an activity your students might enjoy, you can find it in my TeachersPayTeachers store.
