OLD TOWN – There is Planet Earth, which, for the sake of the discussion taking place in Ed Lindsey’s 9th-grade science class at Old Town High School, is a spherical object made of rock, watery on its surface and wrapped in a layer of air. And there is the mysterious Planet Z, identical to Earth in every way, but without air or water. The two planets revolve around an identical star at the same distance and speed.

Here’s the question that Lindsey’s Earth Science students are exploring: How will the energy of the sun differently warm these two planets?

“Planet Z will heat up slower, but eventually will be hotter than the Earth at the equator, “ said student Jaime Lemery, “but Earth will be warmer at the poles.”

That’s the hypothesis she and her lab partner Rowan Shelly were planning to test, based on their mental image that water molecules are “freer” than molecules of rock and therefore transfer heat more readily.

Lindsey’s 9th-graders are among hundreds of students benefitting from a partnership between UMaine and regional public schools. The Penobscot River Educational Partnership’s Earth Science Collaborative draws participation from Old Town, Orono, Bucksport, Hermon, Hampden and Brewer. The collaborative also receives input and support from several programs at the University of Maine, including the College of Education and Human Development, the College of Engineering, and the Maine Center for Research in STEM Education, which promotes career paths in science, technology, engineering and mathematics.

The group strives to create and support an engaging 9th-grade Earth Science curriculum that will respond to the variable developmental levels of high school freshmen and prepare them for the rigors of upper-level classes in biology, chemistry, and physics. With help from PREP partners at UMaine, the participating schools have developed elements of a curriculum that gets youngsters grappling with big-picture science concepts within the framework of Earth Science.

“What we’ve tried to do is complicated but worthwhile,” said Lindsey, a 1984 UMaine graduate. “It is to develop deep understanding of a few concepts that have explaining power over many topics and disciplines — examples are the behaviors of systems, energy, and energy transfer, the balance of forces and resulting motions — and to impart in citizens a sense of the connectedness of Earth’s systems.”

For Lindsey and his Old Town High School colleague Lisa Schultz, that means getting students talking about big scientific ideas rather than about a lot of specific facts. It means introducing them to the language and culture of the science lab, the scholarly practice of evidence-backed debate, and the value of being able to articulate and defend their ideas coherently.

“What we want them to be doing is engaging in inquiry,” he said, “not just filling up their heads up with facts.”

For the planet-warming inquiry, the students in Lindsey’s and Schultz’s labs are using some specialized equipment developed at UMaine. Each pair of lab partners is assigned two narrow, tabletop troughs made of clear plastic. Designed to the teachers’ specifications, the troughs were assembled at the Advanced Manufacturing Center on campus.

The students fill one trough – “Earth” – with room-temperature water. The other gets filled with dry, pebbly material that looks like fish tank gravel – that’s the mysterious, waterless Planet Z. A lamp with a bright incandescent bulb shines on the center of the two troughs, hot as the sun.

The students outfit each of their planet models with electronic temperature sensors, one in the center of the trough and the other at one of the ends, representing the equatorial and polar regions of the planet respectively. Data-carrying cables from the four sensors are joined into a single strand, wired to a thumb-sized circuit board and plugged directly into the USB port of the students’ school-issued laptop computers.

Developed and manufactured last semester by UMaine engineering students, the “UMeter” sensor is designed to be low-cost and user-friendly. It feeds a continuous stream of temperature data into the spreadsheet program installed in the no-frills laptops, bypassing the need for any additional software or programming.

Although Lindsey’s students are not currently working with peers in other schools as part of the planet-warming project, the technology is available to gather data from multiple classrooms throughout the state, crunch their numbers simultaneously ,and create a giant, multi-screen graph of the temperature readings on Planet Earth and Planet Z.