Hey Adam,
I have done this exact thing, but built it around hydroponics. Students began with the basics and worked their way up to learning how to wire and code various sensors to monitor variables within the system.
Students were then charged to create an actuator that responded to these variables as they crossed thresholds in order to not only monitor them, but automate their adjustment.
Finally, we integrated their projects on the arduino with raspberry pi so they could be remotely monitored and controlled and have their data analyzed over the course of a crop rotation on an IoT dashboard.
They way I instructed them was by creating videos ahead of the lessons in which I assembled the circuits and wrote the code. This freed me up to wander the room and make adjustments instead of having it be teacher-centric. It also allowed them to watch the instruction ahead of time as well as review it afterward. All videos were edited to help make them easier to follow and more user friendly.
Students earned digital badges with each successful challenge. I intend to extend these projects into our FarmBot in order to have a side-by-side comparison of the challenges involved with robotic farming in both hydro and traditional soil. It is my longterm goal to design and 3D print new tools for the FarmBot with the kids as part of this process. I work with 12-14 year olds in an after school coding and engineering club. You can check out some of our work @reginius214 on Twitter and Instagram and can take a look at some of the instructional videos I was referring to on YouTube on ReginiusScience. I am by now means trying to sell you anything. Just want to give you an idea of some of our projects. Feel free to DM with questions.
Best,
Chris Regini
Raspberry Pi certified science teacher
NewYork, USA