Engineering and Testing a Soil Moisture Sensor

byJhansi Sunkerneni

With the ever increasing human population, the need for water cannot be underestimated. It is today’s pressing issue and we need to act on it now, to conserve water. Future water shortages can lead to drastic impacts on food production, other ecosystems, and the environment. If water conservation is not practiced, the world could face irreversible consequences. In this curriculum unit my goal is to introduce the need to conserve water, the impacts of water shortage problems, how working as a team can help towards solving this global problem, and how to build and test a soil moisture sensor that can benefit farmers by not having to water farmland when it is already moist.

This unit is built to help teachers who are new to the field of Engineering to basic background knowledge of what they need to know in order to help their students build an electronic device. Students will learn about the engineering design process involved in building a soil moisture sensor. They will then learn about basic electronic components and their function. Then, they will then apply their knowledge, to build a basic circuit to light up an LED bulb. The end goal is to build an electronic soil moisture sensor with their teams, test it, analyze and communicate the results, and essentially use it in their backyards, and be ready to experiment to build other electronic devices. This unit was developed for Engineering Design, Grade 7 students.

(Developed for Science, grade 7; recommended for Science, grade 7)


Comments (1)

    Jhansi Sunkerneni (College Connection Academy, San Jose, CA)
    Subject taught: Science , Grade: 7
    Soil Moisture Sensor Reflections
    I was able to complete this unit with students, as students are back in the classroom after Covid.
    Here is a summary of my reflections:

    Students who didnít finish this project got help from teams that completed early.
    80% of the students were able to complete building and testing the soil moisture sensor.

    Some of the challenges that students faced are listed below:

    Short circuited the snap connector and the battery. Had to cut, strip the wire, and twist the wires before inserting it in the breadboard a second time.
    Made wrong connections, as they didnít follow the instructions carefully. Fixed the problem by re-reading the instructions and following the instructions carefully.
    Using the wrong resistors in the circuit. Realized later, that the resistors that need to be connected to the soil must be the 100K Ohm resistors.
    The wires were loosely connected to the breadboard. Corrected the problem, by ensuring that the wires were connected securely.
    The snap connector was not connected correctly. Figured out the positive and the negative markings on the battery, and made the correct connections.
    The LED bulb didnít glow due to polarity (placed incorrectly in the breadboard). Fixed the problem, by making the correct connection of the leads.

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