When Plants Speak: Learning Through Making for Sustainable Plant Care

Students begin by observing a plant and discussing what it needs to stay healthy. They then explore different types of soil by observing and comparing their colour, texture, moisture, and appearance. Through hands-on observation, students start connecting the characteristics of soil with plant growth and plant needs.

Students experiment with plants by giving them different amounts of water and sunlight and observe what happens over time. They look for simple changes such as leaf colour, drooping, growth, and how wet or dry the soil feels. They record and compare their observations and discuss what helps a plant stay healthy.

Through this activity, students experience a real challenge: it is not always easy to tell exactly what a plant needs just by looking at it. This naturally leads them to think about how we could help the plant communicate its needs. They will try to understand the language of plant.

In this step teacher starts by asking:

“What if we are not around to check the plant every day? How would we know if it needs water or more sunlight?”

Students share their ideas based on what they have seen during the experiment. They might suggest touching the soil, looking at the leaves, or checking how the plant is growing.

The teacher then takes the discussion a little further:

• How can we know if the soil is too dry or has enough moisture?
• How can we tell if the plant is getting enough sunlight?
• Is there a way for the plant to tell us what it needs?
• Can we find a way to know what the plant needs even when we are not there?

Students think about possible solutions and share their ideas. Technology is not introduced immediately. Instead, students first understand the problem and realise that simply looking at the plant may not always be enough.

The teacher then introduces the challenge:

“Can you find a way to help the plant speak to us and tell us when it needs water or sunlight?”

This challenge naturally creates curiosity about how sensors and simple electronics could help the plant communicate with us.

Now that students have experienced the challenge, the teacher asks:

“What if we could give the plant a way to communicate with us?”

Students explore a soil-moisture sensor and a light sensor and connect them to what they observed during the plant experiment.

• The soil-moisture sensor tells us whether the soil is wet or dry.
• The light sensor tells us about the amount of light the plant receives.
• Students observe how sensor readings change under different conditions.
• They discuss how these readings can help us understand what the plant needs.

“The sensor cannot speak like us, but it can give us information about what the plant is experiencing.”

Students now turn their ideas into a working system. Before starting, the teacher revisits the question:

“How will our plant tell us what it needs?”

Students identify the role of each component:

• Soil-moisture sensor → detects whether the soil is dry or wet.
• Light sensor → detects the amount of light.
• Arduino → acts as the plant’s “brain” and makes decisions.
• LEDs → act as the plant’s “voice” and communicate its needs.

Instead of simply giving students a wiring diagram to copy, the teacher encourages them to think about how the components work together.

Teacher: “The soil sensor tells us the soil is dry. Who will decide what that means?

Students: “Arduino!”

Teacher: “And how will the plant tell us that it needs water?”

Students connect this idea to the LED indicators they designed earlier.

Teams then build the circuit step by step. They first connect and test one sensor, then add the second sensor and finally the LEDs. This helps students identify problems more easily.

The teacher can guide them with questions:

• “What does this sensor measure?”
• “Where does the information go?”
• “What will happen when the soil is dry?”
• “Which LED should communicate that message?”

The goal is not to build a perfect circuit immediately, but to help students understand that building, testing, finding errors, and fixing them are all part of engineering.

Once the circuit is ready, students give their plant a “voice” using simple If–Then rules.

The teacher introduces the idea without code:

“If the soil is dry, then what should the plant say?”

Students create rules such as:

IF soil is dry → THEN blue LED turns ON.

IF light is low → THEN orange LED turns ON.

IF soil and light are good → THEN green LED turns ON.

Students first write these rules on paper and then convert them into Arduino code. This helps them understand that programming means giving clear instructions to make decisions.

The teacher then introduces thresholds:

“The sensor doesn’t understand ‘dry’ or ‘wet.’ It gives us a number. We need to decide which number means the soil is dry.”

Students test sensor readings and choose a suitable threshold.

The LEDs become the plant’s voice:

Green → “I am happy.”

Blue → “I need water.”

Red → “I need sunlight.”

Further students can add CO2 sensor – to understand if plant use to release CO2 in night? or pump for pouring water automatically.

Students now give their “Plant Speaks” system a neat, finished look. They cover the LEDs with simple diffusers and place the Arduino, wires, and other components neatly inside a box, while keeping the sensors connected to the plant. Paper boards telling words of plant will be placed

Students then test the system with dry/wet soil and different light conditions and observe whether the correct LED communicates the plant’s needs

Students test their “Plant Speaks” system under different conditions, such as dry or wet soil and bright or low light. They observe whether the correct LED communicates the plant’s needs.

If the system behaves unexpectedly, students identify the problem and make improvements by adjusting the circuit, code, or sensor thresholds. They test again to check whether their changes have improved the solution.

“Build, test, find the problem, improve, and test again.”

Teams demonstrate their “Plant Talk” system and explain how the sensors and LEDs help the plant communicate its needs. Students share what they learned, the challenges they faced, and how they improved their solution. Here is the video of how plant talk system works