Automated soil moisture sensor
About this lesson
The soil moisture sensor project integrates science understandings and computational thinking to solve a problem about sustainable watering practices. This lesson was devised by Trudy Ward, Clarendon Vale Primary School, Tasmania.
Year band: 3-4, 5-6Curriculum Links Assessment
Links with Digital Technologies Curriculum Area.
Define simple problems, and describe and follow a sequence of steps and decisions (algorithms) needed to solve them (ACTDIP010)
Implement simple digital solutions as visual programs with algorithms involving branching (decisions) and user input (ACTDIP011)
Design, modify and follow simple algorithms involving sequences of steps, branching, and iteration (repetition) (ACTDIP019)
Implement digital solutions as simple visual programs involving branching, iteration (repetition), and user input (ACTDIP020)
Links with Design and Technology Curriculum Area.
Select and use materials, components, tools, equipment and techniques and use safe work practices to make designed solutions (ACTDEP016)
Evaluate design ideas, processes and solutions based on criteria for success developed with guidance and including care for the environment (ACTDEP017)
Select appropriate materials, components, tools, equipment and techniques and apply safe procedures to make designed solutions (ACTDEP026)
Negotiate criteria for success that include sustainability to evaluate design ideas, processes and solutions (ACTDEP027)
Links with Science Curriculum Area.
Living things depend on each other and the environment to survive (ACSSU073)
Living things have structural features and adaptations that help them to survive in their environment (ACSSU043)
A celebration of learning enables students to show other teachers, peers and community their solution. This also forms part of their assessment; their ability to communicate their design process and product.
A rubric is one form of summative assessment you can use to determine students' processes and evaluate their success.
Students can keep a design journal for assessment, detailing their design steps and progress for assessment.
All of the project's assessments are based upon the Australian Curriculum: Digital Technologies achievement standards. The heart of the project is how the Digital Technologies curriculum integrates with students' understanding of real-world problems and, through decomposing those problems, how the students identify key elements and factors that enable them to find potential solutions not possible by using algorithms, programming and digital systems to bring about change (Curran, 2017). Students also show the ability to work as part of a team, with some autonomy.
- Investigate factors that affect plant growth.
- Collect data using a sensor.
- Program coding software to automate the watering of a plant.
- Evaluate the results of the watering system.
Anxiety/ Additional scaffolding:
Cater for students with social/emotional challenges. Consider adjustments to ensure that students facing these challenges feel comfortable while completing the project.
Remember that you can make adjustments to lighting and room noise levels.
Consider an initial meeting with students to discuss the project and their needs. For students with autism spectrum disorder (ASD), this will support the scaffolding of necessary social stories and routines so the students will be able to participate to the best of their ability. Duncan, Ruble, Thomas & Stark (2017) discuss how crucially important the creation of an environment that includes pedagogical practices of scaffolding and reinforcement is to students with ASD remaining engaged in school.
Other students in the class may have behavioural issues and come from all-too-common trauma backgrounds. You can also meet their needs through close consultation over their learning plan, and through the practice of calmer classrooms trauma pedagogies to ensure a calm, safe space where they feel valued and respected. The aim is to create a hands-on inquiry environment where a culture of measured risk-taking within the task is accepted and encouraged (Geary, 2007).
- Identifying the problem
Engage students in the project by using a relevant hook (such as a visit to a local garden, school vegetable garden, agricultural farm or similar context) to discuss sustainable watering practices. Discuss an automated process (such as one using a sensor to gather data about soil moisture) and how this might work.
- Investigating and defining
Using a collaborative approach and a teacher as facilitator, pose the problem in the form of this question: ‘How can we achieve optimal plant growth using sustainable water practices?’
Students investigate and define the problem, considering the germination and growth of plants. To solve this real-world problem, they brainstorm and research potential solutions using the internet and graphic organisers – such as mind maps or ‘T’ charts – to communicate what they currently see, and what they expect to see. Albion, Campbell & Jobling (2018) support this type of collaborative inquiry, and this pedagogical practice, as it provides students with necessary enterprise skills required for real-world projects.
Credit: Trudy Ward
- In each group, students should give consideration to each other’s ideas, skill sets and preferences. This will help to determine both the type of solution they would like to create and how they could realistically achieve the necessary processes required to create a product suitable for its intended purpose.
- Generating and designing
Encourage students to decide on an approach to implementing their digital solution through a process of elimination. This process should consider affordability and other relevant criteria, which may include ease of use/programming. Ask students to justify their choice. For example, a suitable solution may include BBC micro:bit and Grove Seeed kit to create a soil moisture sensor for data collection. Justification may include the ability to analyse and evaluate data for the purpose of keeping the soil moisture at optimal levels for seedling germination and growth.
- Discuss approaches such as peer assessment of the coding to ensure that errors are mitigated and that a collaborative approach is used to build mutual friendship and trust. Through becoming aware of a problem, identifying a data source and proposing an automated sensor, students are using computational thinking. They are allowing their current thoughts, learnings and outcomes to be transformed through coding, which requires a precise form of language to enable a system to operate (Henderson & Romeo, eds, 2015).
- Discuss assessment criteria for the project and develop a rubric to ensure students have input into each of the key stages of the design project. The rubric can increase productivity if students refer to it at any stage to monitor their progress and to help them stay on track.
- Producing and implementing
In this example it is suggested students use a programming board such as the BBC micro:bit. Students can use the Makecode website to create code for their project using visual programming. Micro:bit enables the use of sensors.
Credit: Trudy Ward Makecode user interface and student programming
The first stage is to program their Micro:bit to gather data on moisture level.
A sample program is provided to help guide students with the process.
Students test their soil moisture sensor with a pot plant and evaluate how well the system works.
Future ideas and modifications
Students may discuss or implement changes or modifications, for example:
- Incorporate a solar panel attachment to the battery, so the battery will continually charge and not go flat.
- Conduct the test using the sensor in multiple conditions such as the glasshouse, the classroom and outside to see the extent to which other environmental factors affect plant growth.
Digital Technology focus
- What did you learn as you created your program to automate the watering of a plant?
- What parts of the code did you use to connect and operate the sensor?
- How is your digital solution sustainable?
- What did your investigation of plant germination and growth reveal?
- How much water does a plant need and how did you find that out?
Why is this relevant?
Students implement simple digital solutions as visual programs with algorithms involving branching (decisions) and user input.
First, some definitions:
Implementing a decision in a programming language, usually using an ‘if’ or ‘if-else’ statement.
Students can create programs that include some form of decision, such as writing simple if-statements.
Receiving data from the user (via a sensor or direct input with a keyboard, mouse of other input device) and using that data in code.
In this program, students gather data using a moisture sensor. This data is then used to execute some action.
In years 5–6, students are also expected to incorporate iteration (loops).
The repetition of block of instructions in a programming language, based on some kind of test condition. These instructions include looping constructs such as 'while', 'for' and 'repeat until'.
Students can implement loops in their program that repeat a given number of times, continue until a certain condition is met, and may include variables and values that change inside the loop and trigger its exit condition.
Albion, P., Campbell, C. & Joblin, W. (2018). Technologies education for the primary years. First edn. Cengage Learning Australia
Duncan, Ruble, Thomas & Stark (2017). A 6-month follow-up of a daily living skills intervention for high functioning adolescents with ASD. (Web program paper). Golden Gate Ballroom (Marriott Marquis Hotel), May 10–13, 2017. Last referenced 3 April 2019: https://insar.confex.com/insar/2017/webprogram/Paper24447.html
Geary, B. (2007). Calmer classrooms: A guide to working with traumatized children. Melbourne, Victoria: Child Safety Commissioner.
Henderson, M. and Romeo, G. (eds). 'Teaching and digital technologies: big issues and critical questions', The Curriculum Journal, 27(4), 560–561
Saeli, M., Perrenet,J., Jochems, W. & Zwaneveld, B. (2011). Teaching Programming in Secondary School: A Pedagogical Content Knowledge Perspective. Informatics in Education, v10 n1, 73-88
Turing, A. M. (1950). Computing Machinery and Intelligence. Mind 49: 433-460.