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Build a Robot with a Green Thumb

What unique, creative, and interesting solutions do you think your students could devise when presented with this challenge?

Your challenge is to design and build a sensor-controlled watering system for a potted houseplant using your EV3 robotics kit. Your device should automatically water the plant when the soil is too dry but also stop when the soil is sufficiently wet. You will use a Vernier Soil Moisture Sensor to monitor the moisture level of your plant’s soil. The soil will be considered “too dry” when the moisture level falls below 20%, and sufficiently “wet” when the moisture level rises above 28%.

The programming and constructing of a sample solution for this challenge are clearly outlined in the teacher’s section of our Vernier Engineering Projects with LEGO® MINDSTORMS® Education EV3 lab book. In our sample solution, we attach a LEGO® pneumatic pump to a LEGO® motor. A clear plastic water bottle is equipped with a 2-hole stopper, and tubing attaches from the bottle to the pump and from the bottle to the plant. We program this robot using a MINDSTORMS® Loop block that continuously monitors the reading from the Soil Moisture Sensor. If the reading is within the range, the robot does nothing; but if it falls below the threshold value, the program activates the motor to pump air into the bottle and push water out to the plant. The program waits to allow the water to percolate and loops back to monitor the sensor reading again.

When presenting this challenge to your students, one option is to share some, or all, of the sample solution with them. Another option is to have your students fully take on the challenge by allowing them to come up with their own distinct solution. This will undoubtedly lead to some truly imaginative, interesting, and fun ways to transport, carry, or splash water on a thirsty plant. For students who finish early or who want to pursue an independent project, the book also provides project extension ideas. In one project extension, a robot monitors the amount of light that the plant receives. If the light is too low, the robot must increase the light or warn the plant owner.

A real-world challenge like this introduces your students to the engineering design process. Students learn about robotics and programming, delve deeper into scientific principles, discover how sensors work, and learn how to solve problems as a team.

For an overview of projects to test batteries, locate hidden magnets that represent “land mines,” track the sun with solar panels, and more, see Vernier Engineering Projects with LEGO® MINDSTORMS® Education EV3


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