28 May

Second Installation: Cook-Wissahickon Elementary


Root Kit #2 is in the ground at Cook-Wissahickon Elementary School. This version is a futuristic, light-up LED dome. Admittedly, it’s not that impressive in daylight, but should be an interesting sight as some fiberoptic lights illuminate whenever the sensors take readings (approximately every 10 minutes). It’s situated in a planter bed and sends data to a receiving unit in Mr. Ramos’ second-floor classroom.


Above, the initial setup of the receiving unit (a Raspberry Pi with a JeeLink). It does take some patience and testing to ensure connectivity with the school’s wifi network and determine the best placement for the Raspberry Pi and JeeLink to capture the incoming radio signal from the sensors outside. In these early days of installing greenSTEM sensors at schools, we are lugging around our own monitor, keyboard and mouse to perform the setup procedure; this is something that needs improvement. We’ve attempted many solutions (from hacking an old Motorola lapdock to mirroring the Raspberry Pi on a laptop), but they often result in a system freeze or don’t allow the Pi to make the new wifi connection. Furthermore, the wifi dongle needs to be on a separate, powered USB hub—in short, the Raspberry Pi’s USB ports don’t like too much plugging/unplugging of components and will cause the unit to reboot. A streamlined setup tutorial is on the horizon, most likely this summer. But for now it’s spring—check out how the sensors are responding to rain at Nebinger and Cook-Wissahickon here.

27 May

First Installation: Nebinger Elementary School


The first greenSTEM installation took place last week at George W. Nebinger Elementary School in Bella Vista. The school not only has a new rain garden; it has a new, high-tech rain garden with sensors that allow students to monitor soil moisture in real time via the web. Students can use the data to schedule waterings, analyze meterological patterns, catalog plant species’ watering needs, and correlate environmental data. The sensor kit (called a Root Kit) is tucked inside a spider, the winning design from last month’s student design competition. Data from Nebinger’s garden can now be viewed live on this web page.

Thanks to Ms. Odoroff, her students, George Li from the Philadelphia School District for the technical assistance, and all the helpers who came out to oversee the installation. If the spider looks a little bit worse for the wear in the photo above, that’s largely due to our waterproofing efforts. We used Rust-Oleum LeakSeal (a spray-on rubber coating), and it left some residue. We also ended up poking a hole through the spider’s back for the Root Kit’s antenna; we got a better signal to the 4th floor classroom with the antenna exposed.

Up next: Cook-Wissahickon Elementary School.


08 May

Seeing Daylight


Week 3 at SLA Beeber: Some nice weather made the thought of soldering circuit boards and decorating sensor housings in the classroom unappealing. We jailbreaked to nearby Indian Creek in Morris Park. The west branch of the creek was recently daylighted—the creek had been buried in a sewer in 1928, and the Philadelphia Water Department and the U.S. Army Corps of Engineers recently completed the process of bringing the creek back aboveground. Approximately 750 feet of new stream bed was constructed, and 1,300 feet of stream channel was reconfigured. In the photo above, you can see how the new stream features riffles and pools that serve as habitat for fish and aquatic invertebrates. A blog post at phillywatersheds.org has more detail.

02 May

Eyeballs and Circuits


Week 2 at Science Leadership Academy’s Beeber campus saw the students begin constructing two aspects of the Root Kit: the circuit board (a JeeNode, which is a low-cost, low-power microcontroller with a radio transceiver) that controls the sensors, and the artistic housing that will cover the Root Kit outside in the garden. One group of students soldered while the other group painted.


We followed JeeLabs’ excellent step-by-step instructions to solder the microcontroller boards. The students are charged with creating their own do-it-yourself manual for creating Root Kits, and their main tips for soldering were 1) Keep track of how long the solder wire is—too long and you don’t have much control, too short and you increase the risk of burning yourself; and 2) Soldering gets easier as you go along. Definitely good advice.


The students also got to work on their two housing designs: an eyeball (above), and a crashed rocketship. The eyeball came together quickly: acrylic paint, some glitter glue, and a plastic bowl. It looks excellent—I hadn’t considered how these designs need to be bold and simple; they should be apparent amid garden vegetation from a third-floor classroom window 100 feet away. The eyeball achieves that. More on the rocketship design next week, as we didn’t have quite the right cutting tools for the plastic fins. Student tip for working with recycled 2-liter soda bottles: Use a base coat of white paint first, then put a color coat (in our case, silver) over top of it. The first coat doesn’t adhere well to the bottle’s plastic.

A word of advice for procuring housing materials: Dollar stores are your friend when you can’t find recycled plastics that fit your design needs. Ideally, we’d use recycled materials 100% of the time, but sometimes exceptions are made. Just make those exceptions as cheaply as possible.