Biology
Biology is often seen as a “soft” science—more about observation than measurement. But in truth, it’s full of motion, cycles, energy, and structure—all of which can be captured and quantified using the sensors in a smartphone.
This chapter turns living systems into living data: from the tilt of a growing stem to the bubbles of fermenting yeast, from the tiny mouths of a leaf to the swirling microbes in a drop of pond water. With just a camera, a light sensor, or a clip-on microscope, students can explore growth, metabolism, communication, reproduction, and even how plants respond to stress.
Some experiments are classics—reimagined through a modern lens. Others use AI-powered tools for identification, analysis, or explanation. But all share the same spirit: low-cost, ethically clean, and powered by curiosity, careful observation, and wonder.
https://static.publiclab.org/#wiki/near-infrared-camera
Build Your Microscope
$10 Smartphone to Digital Microscope Conversion (BIO-01)
Sensors Used: Camera
What’s Measured: Visual magnification of microscopic specimens
Description
Turn your smartphone into a digital microscope using just a few low-cost materials. By attaching a small lens (such as a laser pointer lens or clip-on macro lens) to your phone’s camera and building a simple stand from cardboard, plastic, or recycled materials, you can achieve surprisingly high magnification.**
This setup allows you to observe tiny structures—like plant cells, insect parts, or fibers—by using your phone’s camera to both view and record what you see. The result is a powerful, portable tool for exploring the microscopic world, perfect for science class or field investigations.
References:
[1] “$10 Smartphone to Digital Microscope Conversion!,” https://www.instructables.com/id/10-Smartphone-to-digital-microscope-conversion/
Foldscope: The Paper Microscope (BIO-02)
Sensors Used: Camera
What’s Measured: Microscopic structures (via optical magnification)
Description
The Foldscope is a low-cost, origami-style microscope made from a single sheet of paper and a tiny lens. Designed to democratize access to science, it offers up to 140× magnification and 2-micron resolution — enough to see cells, microorganisms, and fine structures in nature.**
Attach your smartphone camera to the Foldscope to capture photos or videos of your observations. Its lightweight and durable design makes it perfect for field biology, classroom use, or backyard discovery — no power outlet or lab bench required.
References:
[1] “Foldscope: A Paper Microscope You Can Attach to Your Smartphone,” https://spectrum.ieee.org/geek-life/tools-toys/foldscope-a-paper-microscope-you-can-attach-to-your-smartphone
PNNL Smartphone Microscope (BIO-03)
Sensors Used: Camera
What’s Measured: Microscopic detail of biological or material samples
Description
Developed by researchers at Pacific Northwest National Laboratory (PNNL), this clip-on smartphone microscope offers high magnification and resolution in a compact, user-friendly design. It attaches directly to your phone’s camera and allows for detailed imaging of cells, fibers, microbes, and other microscopic structures.**
Designed for portability and ease of use, the PNNL microscope is well-suited for both classroom exploration and field research, bringing professional-quality microscopy to the palm of your hand.
It’s a powerful example of how cutting-edge science can be made accessible through clever, compact design.
References:
[1] “PNNL Smartphone Microscope,” https://availabletechnologies.pnnl.gov/technology.asp?id=393
Pocket Microscopy: Exploring the Microworld with Your Smartphone (BIO-04)
Sensors Used: Camera
What’s Measured: Microscopic features of everyday biological materials
Description
With just a droplet of water or a clip-on macro lens, a smartphone can transform into a functional microscope, opening a window into the hidden details of the natural world. This experiment invites students to explore fine biological structures in everyday materials—from the delicate veins of a leaf to the ridges of human skin, the intricate design of an insect wing, or even the tiny organisms found in yogurt or pond water. By carefully placing a droplet of water over the camera lens or attaching a macro adapter, students can achieve surprising magnification using devices they already carry.**
Lighting and stability are key to success; shining a light from the side and keeping the phone steady can dramatically improve image clarity. With this simple setup, students can document and analyze morphology, study surface textures, and get hands-on experience with the kinds of structures often reserved for lab-grade microscopes. It’s a low-cost, high-impact way to bring the microworld into focus.
Microscopic Life: Cells, Spores & Microbes
Tiny Mouths of the Leaf: Observing Stomata Under the Microscope (BIO-05)
Sensors Used: Camera (with clip-on or DIY microscope lens)
What’s Measured: Structure and density of stomata
Description
Although plants don’t have lungs, they still breathe—exchanging gases and regulating water loss through tiny pores called stomata. With a simple preparation technique and a smartphone microscope, students can observe these vital structures up close. The process begins by applying a thin layer of clear nail polish to the underside of a leaf. Once the polish dries, it is carefully peeled away using transparent tape and transferred to a microscope slide. When viewed under magnification, the stomata appear as small oval openings, often flanked by distinctive guard cells that control their opening and closing.**
Students can capture detailed images of these features and use AI tools to count the number of stomata in a given area or explore how their size and distribution vary under different environmental conditions. Comparing leaves from sunny and shaded areas, or from dry versus moist environments, reveals how plants fine-tune their gas exchange strategies to suit their surroundings. This experiment makes an invisible biological process both visible and measurable, bringing plant physiology into sharp focus.
Pond Life Safari: Discovering Microorganisms with a Smartphone Microscope (BIO-06)
Sensors Used: Camera (with clip-on or DIY microscope lens)
What’s Measured: Observation and identification of aquatic microorganisms
Description
A single drop of pond water holds an astonishing world of microscopic life, and with a smartphone microscope, students can embark on a true biological safari. By collecting samples from a local pond, stream, birdbath, or even a neglected plant tray, students gain access to a diverse ecosystem filled with protists, algae, and tiny invertebrates. A drop of this water placed on a slide becomes a window into this bustling microworld, where movement and structure can be observed in real time through a DIY or clip-on microscope lens.**
As students explore and record what they see—capturing photos or videos of organisms in motion—they begin to document the hidden biodiversity around them. These visual records can then be analyzed with the help of AI tools, asking questions such as, “Can you help identify this one-celled organism?” or “What kind of protist moves like this?” The results can be compiled into personal field guides, collaborative microbe galleries, or digital biodiversity posters. It’s a vivid and accessible way to explore microbiology, ecology, and the diversity of life that thrives just beyond the range of the naked eye.
Fuzzy Forests: Observing Mold Spores with a Smartphone Microscope (BIO-07)
Sensors Used: Camera (with clip-on or DIY microscope lens)
What’s Measured: Growth and structure of fungal hyphae and spores
Description
Mold may seem like a sign of decay, but under magnification, it transforms into a complex and beautiful miniature forest of branching hyphae and spore-producing structures. In this experiment, students cultivate mold on slices of bread, fruit, or cooked rice, allowing colonies to grow naturally over the course of several days in a loosely sealed container. Once the mold becomes visible to the naked eye, they use a smartphone microscope to dive into the hidden structures behind fungal reproduction.**
Viewed up close, these colonies reveal intricate hyphal networks and distinctive spore formations, with variations in shape, branching patterns, and pigmentation. Students can photograph their observations and bring in AI tools to help identify what they’re seeing, asking questions such as, “Can you help me identify this spore structure?” Comparisons between genera like Rhizopus, Penicillium, and Aspergillus can spark discussions about fungal diversity, structure, and life cycles. This experiment offers a hands-on introduction to the field of mycology and highlights how everyday biological processes become newly fascinating when examined through the lens of a microscope.
The Cell City: Exploring Plant Cells with a Smartphone Microscope (BIO-08)
Sensors Used: Camera (with clip-on or DIY microscope lens)
What’s Measured: Visible structures in plant cells
Description
Plant cells hold the architectural blueprint of life, and with a smartphone microscope, students can observe their inner structures firsthand. This experiment reimagines a classic biology lab by using an onion skin or a small Elodea leaf to reveal the hidden components of the cell. A thin peel of onion epidermis or a delicate aquatic leaf is placed on a microscope slide with a drop of water and covered with a slip, creating a simple but effective window into plant anatomy.**
Under magnification, students can clearly observe rigid cell walls and prominent nuclei, while in the case of Elodea, chloroplasts may be seen gently streaming through the cytoplasm in a mesmerizing display of cytoplasmic movement. Photos of these observations can be analyzed with AI tools to help label structures or explain organelle functions, turning microscopic imagery into interactive learning. By comparing samples—or even juxtaposing plant cells with animal cells—students begin to grasp the remarkable organization and specialization that underlie all living systems.
Growth & Movement: Plant Dynamics
Watching Plants Grow: Time-Lapse Photography of Tropism (BIO-09)
Sensors Used: Camera
What’s Measured: Growth, movement, and directional response of plants over time
Description
Plant movement is real, but it unfolds on a timescale too slow for the human eye to catch. Using time-lapse photography, students can bring these subtle processes into view, capturing how plants respond to their environment through changes in growth and orientation. A smartphone placed on a stable surface or tripod becomes the perfect tool for documenting this slow choreography. By taking regular photographs—either hourly or daily—students can stitch together a time-lapse video that reveals how plants stretch toward light, adjust leaf angles, or react to gravity over time.**
This experiment becomes even more engaging when variables are introduced. Rotating a light source encourages phototropism, where plants bend toward the light, while tracking changes in leaf orientation may uncover daily rhythms tied to internal circadian cycles. The resulting video transforms what once seemed static into a vivid, measurable display of biological responsiveness, demonstrating how plants interact with their surroundings in dynamic, data-rich ways.
Bending Without Muscles: Exploring Phototropism and Geotropism (BIO-10)
Sensors Used: Camera, angle measurement app (e.g., protractor app)
What’s Measured: Growth angle in response to light and gravity
Description
Though plants lack muscles, bones, or nerves, they are remarkably capable of movement—relying on hormones and internal signaling to respond to their environment. In this experiment, students investigate phototropism and geotropism by altering the orientation of a plant and tracking how it bends in response to light and gravity. Seedlings grown in tilted pots begin to curve upward, defying gravity, while rotating a plant container each day can lead to surprising shifts in growth direction as the plant reorients itself toward the light.**
By photographing the plant daily and measuring the changing angle of the stem with a smartphone protractor app, students can plot a dynamic curve that illustrates how the plant senses and adjusts to its surroundings. These slow, graceful movements tell a powerful story of adaptation driven not by conscious thought, but by elegant biochemical pathways. This hands-on investigation reveals the hidden intelligence of plants—showing how they grow, adapt, and survive without ever taking a step.
The Hidden Clock: Observing Circadian Rhythms in Plants and Fungi (BIO-11)
Sensors Used: Camera (time-lapse), optional light and temperature sensors
What’s Measured: Daily rhythmic movement and growth patterns
Description
Living organisms have internal clocks that tick even in the absence of sunlight, guiding their behaviors in remarkably consistent cycles. In this experiment, students use time-lapse photography to uncover the circadian rhythms of plants and fungi—natural, daily patterns of movement and growth driven by internal biological timing. A bean plant, morning glory, or even a suitable fungus becomes the subject of observation, with a smartphone camera capturing its subtle behaviors over several days.**
Students may witness leaves rising and falling, flowers opening and closing, or distinct spurts of growth occurring at the same time each day. For additional insight, they can pair these observations with light and temperature data collected via smartphone sensors. Perhaps most revealing is the follow-up question: what happens when the organism is kept in continuous darkness? Even without external cues, the rhythms often persist—evidence of internal regulation. This simple but elegant experiment introduces students to the concept of circadian biology, gene expression cycles, and how life remains in sync with the environment even in the absence of visible change.
Sprouting Science: Tracking Seed Germination in a Window Garden (BIO-12)
Sensors Used: Camera, optional ruler or image measurement tools
What’s Measured: Germination timing, root and shoot growth
Description
Seed germination is one of biology’s most accessible and rewarding transformations to witness. In this experiment, students create a simple window garden to explore how environmental factors influence the emergence and early development of plants. By placing common seeds—such as beans or lentils—between moist paper towels inside a transparent plastic bag or container, and positioning it in a bright window, students can monitor the entire germination process up close.**
Each day, they capture images to track root and shoot length, record the time to germination, and observe how the young plant responds to its surroundings. For deeper insight, students can experiment with different environmental conditions—comparing growth in light versus darkness, warm versus cool temperatures, or moist versus drier setups. The option of using time-lapse photography adds a dynamic dimension, turning slow changes into an engaging visual sequence. This experiment offers a gentle but data-rich introduction to plant development, environmental influence, and the early life of a seedling.
Photosynthesis & Gas Exchange
Chasing the Light: Observing Photosynthesis in Action (BIO-13)
Sensors Used: Camera (time-lapse), optional light sensor
What’s Measured: Leaf movement, oxygen release, light response
Description
Photosynthesis powers nearly all life on Earth, yet it often goes unseen. In this experiment, students use a smartphone to make the process visible—capturing how plants adjust to changing light and even releasing oxygen as they work. One approach involves tracking leaf movement over time. By exposing a plant to cycles of light and dark and using time-lapse photography, students can observe leaves gradually shifting their orientation, an adaptive behavior that maximizes light capture for photosynthesis.**
A second method brings gas exchange into view. By submerging small leaves such as spinach or Elodea in water and placing them under a bright light, students may begin to see tiny oxygen bubbles forming on the leaf surfaces. These bubbles offer tangible, visual proof that photosynthesis is actively converting light into chemical energy. For added depth, a light sensor app can help correlate light intensity with observed activity. Whether through motion or gas release, this experiment reveals the living mechanics of photosynthesis in a way that’s accessible, beautiful, and grounded in everyday observation.
The Sweating Leaf: Measuring Transpiration with a Plastic Bag (BIO-14)
Sensors Used: Camera (time-lapse), optional humidity or temperature sensor
What’s Measured: Water vapor release (transpiration rate)
Description
Though seemingly still, plants are constantly at work moving water through their tissues and into the air. This process, known as transpiration, becomes visible in this simple and revealing experiment. By enclosing one or more healthy leaves in a clear plastic bag and gently sealing it around the stem, students can watch moisture accumulate on the inside of the bag over the course of a few hours. The condensation that forms is water vapor released from the plant through stomata—tiny pores that control both gas exchange and water loss.**
Students can enhance the investigation by capturing time-lapse images to document the progression of condensation, weighing any water that collects as droplets, or using smartphone-based humidity or temperature sensors to explore how environmental conditions affect transpiration. This elegant setup offers a hands-on look at plant physiology and environmental interaction, helping students understand how plants regulate moisture and contribute to larger ecological cycles—one invisible breath at a time.
Measuring Green: Estimating Leaf Surface Area with a Camera (BIO-15)
Sensors Used: Camera
What’s Measured: Leaf surface area (as a proxy for photosynthetic potential)
Description
The surface of a leaf is where light meets life—capturing sunlight, exchanging gases, and fueling photosynthesis. In this experiment, students use a smartphone camera to estimate the surface area of a leaf, turning a simple image into a data-rich window into plant function and adaptation. To begin, a leaf is placed flat on graph paper or millimeter paper, then photographed from above under even lighting and with minimal distortion.**
Using image analysis software—or by uploading the photo to ChatGPT for help—students can count the number of pixels within the leaf’s outline, compare it to the grid, and convert that count into real-world measurements. This process transforms a flat photo into a biological dataset. By comparing leaf sizes across different species or between plants grown in sun versus shade, or dry versus humid conditions, students uncover how leaf morphology reflects environmental pressures and photosynthetic needs. It’s a hands-on experiment that merges plant biology with image analysis, showing how simple observations can yield deep ecological insight.
Detecting Photosynthesis via CO₂ Reduction in a Closed Environment (BIO-16)
Sensors Used: CO₂ sensor (Bluetooth or USB), smartphone for logging
What’s Measured: Changes in CO₂ concentration under light vs. dark conditions
Description
Photosynthesis is more than a response to light—it’s a transformation of the atmosphere, as plants pull carbon dioxide from the air to fuel their growth. In this experiment, students make that invisible exchange visible by placing a small plant or leaf in a transparent, airtight bag along with a portable CO₂ sensor. As the plant photosynthesizes in sunlight, it absorbs CO₂, causing the concentration inside the bag to drop. When the plant is kept in darkness, photosynthesis stops, and respiration takes over—releasing CO₂ back into the space and reversing the trend.**
Students can log changes in carbon dioxide using a Bluetooth- or USB-connected sensor and track differences between light and dark conditions in real time. This setup offers a powerful, data-driven view of plant metabolism, highlighting the balance between carbon capture and release. What’s usually invisible in the air becomes a measurable signal of life’s quiet chemistry.
Using pH Indicators to Detect Photosynthesis in Water Plants (BIO-17)
Sensors Used: Camera, optional color analysis app
What’s Measured: pH change as an indicator of CO₂ uptake during photosynthesis
Description
Photosynthesis doesn’t just transform light into energy—it also subtly alters the chemistry of the water around aquatic plants. In this experiment, students use a pH-sensitive dye, such as bromothymol blue, to visualize these changes. When submerged in water with Elodea or a similar aquatic plant, the dye acts as a real-time reporter of CO₂ levels. As the plant photosynthesizes in the presence of light, it removes carbon dioxide from the water, making it less acidic and causing the dye to shift toward blue. In the absence of light, respiration dominates, CO₂ is released, and the solution becomes more acidic, turning greener or yellow.**
Students can document the color shifts using a smartphone camera and optionally analyze the images with a color analysis app to quantify the changes in hue or RGB values. This vivid, accessible experiment offers a clear connection between plant activity and chemical feedback—making the invisible dance of gas exchange suddenly visible in a glass of colored water.
Using a Thermal Camera to Compare Active and Inactive Photosynthesis (BIO-18)
Sensors Used: Thermal camera
What’s Measured: Surface temperature differences due to transpiration and photosynthetic activity
Description
Photosynthesis cools plants—not metaphorically, but physically. In this experiment, students use a smartphone equipped with a thermal camera (such as the CAT S60) to compare the surface temperatures of two similar plants placed side by side: one exposed to direct sunlight and the other kept in shade. Active photosynthesis triggers the opening of stomata, allowing for transpiration—the release of water vapor—which results in a slight but measurable cooling effect. By capturing thermal images of both plants simultaneously, students can detect these subtle differences in temperature. This hands-on investigation introduces key concepts in plant physiology, linking photosynthetic activity, stomatal behavior, and heat regulation in a way that makes these processes visible and measurable.**
Pigments, Color, and Light
Fading Green: Tracking Leaf Color and Chlorophyll Breakdown (BIO-19)
Sensors Used: Camera, optional color analysis app
What’s Measured: Changes in leaf pigmentation over time
Description
Leaves don’t just change color for beauty—they reflect a plant’s internal chemistry and external challenges. In this experiment, students explore how chlorophyll breaks down by observing and analyzing color changes in leaves using a smartphone camera. A few healthy leaves are collected and exposed to varying conditions such as bright sunlight, complete darkness, reduced water, or minor physical damage. Each day, students photograph the same leaves under consistent lighting and use an app to extract RGB color values, tracking the shift from vibrant green to shades of yellow, orange, or brown. These visual changes correspond to underlying biological processes: the breakdown of chlorophyll, the unmasking of carotenoids, and the production of anthocyanins. This experiment invites comparisons between indoor and outdoor samples, and even offers a way to follow natural seasonal transitions—revealing how stress, environment, and age shape a plant’s changing palette.**
Why Apples Turn Brown: Tracking Enzyme Activity with a Smartphone (BIO-20)
Sensors Used: Camera, optional color analysis app
What’s Measured: Rate of enzymatic browning over time
Description
When you slice an apple and watch it slowly turn brown, you’re witnessing biochemistry at work. This experiment invites students to use their smartphone camera to track enzymatic browning—a process driven by the enzyme polyphenol oxidase, which reacts with oxygen in the air. By photographing slices of apple or banana at regular intervals under consistent lighting, students can visually monitor how color changes over time. With the help of a color analysis app, they can quantify these changes by measuring shifts in RGB values. To deepen the investigation, students can test variables like temperature, light exposure, or acidity—applying lemon juice to some slices to explore how pH affects the rate of browning. Through this accessible and edible experiment, enzyme activity becomes something you can see, measure, and understand at the intersection of biology and chemistry.**
Warm Life, Cool Paper: Comparing the Cooling Rate of Living and Non-Living Tissue (BIO-21)
Sensors Used: Temperature sensor or infrared (IR) camera
What’s Measured: Cooling rate of living vs. non-living material
Description
Living things manage energy in subtle, powerful ways—and this experiment reveals just how different they are from inanimate objects. Students compare the cooling behavior of a fresh leaf and a piece of paper after both are gently warmed under a lamp or near a warm surface. Using a smartphone equipped with a temperature sensor or thermal camera, they track how quickly each material loses heat. The results are striking: the leaf tends to stay warm longer, thanks to its higher water content and, potentially, the lingering effects of its metabolic processes. This simple comparison illustrates concepts like thermal inertia and water retention while hinting at deeper biological ideas such as homeostasis. It’s a compelling fusion of biology and physics, showing that even after the heat is gone, life leaves its thermal fingerprint.**
Fermentation & Yeast Activity
Breathing Balloons: Measuring CO₂ from Yeast Fermentation (BIO-22)
Sensors Used: Camera (for time-lapse or periodic photos), optional pressure sensor
What’s Measured: CO₂ production from fermentation
Description
Yeast may be microscopic, but when they get to work on sugar, the results are anything but small. In this experiment, students explore cellular respiration by capturing the carbon dioxide released during fermentation. A simple mixture of yeast, warm water, and sugar is placed in a plastic bottle, and a balloon is stretched over the mouth. As fermentation begins, CO₂ builds up, gently inflating the balloon—a visible and engaging way to witness metabolism in action. Students can document this process through time-lapse photography or by taking periodic photos to track the balloon’s growth. For a deeper quantitative dive, a pressure sensor can be added to measure the buildup inside a sealed vessel, linking gas volume and pressure to the kinetics of respiration and the ideal gas law. It’s an experiment that transforms invisible biochemical processes into something you can watch, measure, and marvel at.**
Yeast Whispers: Listening to Fermentation with a Smartphone Mic (BIO-23)
Sensors Used: Microphone
What’s Measured: CO₂ production rate through sound analysis
Description
Fermentation might look quiet, but it’s alive with sound—if you know how to listen. In this experiment, students use a smartphone microphone to capture the subtle bubbling and fizzing of CO₂ escaping from a yeast culture as it ferments sugar. By placing a phone near a vessel of yeast, warm water, and sugar, they can record the audio of the fermentation process and begin to analyze it. Using waveform visualizers or spectrogram tools, students can examine how the frequency and intensity of bubbling changes over time. These patterns provide insights into the yeast’s metabolic rate and how it’s influenced by variables like temperature, sugar concentration, or yeast type. For more advanced exploration, the audio can be analyzed using FFT tools to reveal rhythmic trends, or uploaded to ChatGPT to extract bubble intervals and overall activity patterns. This experiment brings biology to the ears, transforming fermentation into a rhythmic soundtrack of life at the microscopic level.**
Warm Yeast, Warm Flask: Tracking Heat from Fermentation (BIO-24)
Sensors Used: Temperature sensor, thermal camera
What’s Measured: Heat released during fermentation
Description
Fermentation doesn’t just create bubbles—it gives off heat. As yeast metabolize sugar, they release energy in the form of warmth, making this a tangible example of an exothermic biological process. In this experiment, students set up two flasks: one containing live yeast and sugar to initiate fermentation, and another serving as a control with either boiled yeast or no sugar at all. Using a smartphone-compatible temperature probe or a thermal camera like the CAT S60, students measure the rise in temperature over time. The difference in thermal output between the active and control setups makes the metabolic activity of the yeast visible in real time. This hands-on demonstration links energy conversion, thermodynamics, and biological processes, turning a warm flask into living evidence of cellular respiration.**
Tracking the Buzz: Estimating Alcohol Production from Fermentation (BIO-25)
Sensors Used: Digital scale, optional pressure sensor
What’s Measured: CO₂ production as a proxy for ethanol yield
Description
Fermentation is famous for its fizz, but behind those bubbles lies a chemical transformation that also produces ethanol. Since tasting isn’t an option in the classroom, this experiment takes an indirect route—using mass and gas to estimate alcohol production. Students set up a sealed fermentation vessel containing yeast, warm water, and sugar, and place it on a digital kitchen scale. As the yeast break down the sugar, they release carbon dioxide, which escapes the container and causes a gradual loss in mass. Because CO₂ and ethanol are produced in a 1:1 molar ratio during alcoholic fermentation, students can use the recorded weight loss to estimate how much ethanol has been generated. Alternatively, gas volume can be tracked with a balloon or measured using a pressure sensor. This clever approach transforms invisible chemical changes into measurable data and offers a hands-on application of stoichiometry, metabolism, and energy balance.**
Seeing Cells Grow: Measuring Turbidity with a Smartphone (BIO-26)
Sensors Used: Ambient light sensor or camera
What’s Measured: Turbidity as an indicator of microbial growth
Description
As yeast cells multiply in a nutrient-rich sugar solution, the once-clear liquid slowly turns cloudy—a visible signature of microbial life in action. This experiment transforms that cloudiness, or turbidity, into measurable data using a smartphone. Students prepare several transparent containers with a yeast and sugar mixture and shine a flashlight through each sample. By using the smartphone’s ambient light sensor or camera, paired with a grayscale pixel analysis tool or image-averaging app, they can track how much light passes through the liquid. As the yeast population grows, the light transmission decreases. By collecting and analyzing these readings over time, students can chart a classic microbial growth curve, gaining insight into the dynamics of cell division, population density, and optical density. It’s a powerful demonstration of how microscopic life becomes visible through simple, accessible tools.**
Yeast in Action: Observing Cellular Life Under the Microscope (BIO-27)
Sensors Used: Camera (with clip-on or DIY microscope lens)
What’s Measured: Cellular activity and growth behavior in yeast
Description
Yeast may be single-celled organisms, but under a microscope, they reveal a dynamic and fascinating world. In this experiment, students use a smartphone microscope to observe and compare dormant versus active yeast cells, offering a close-up view of life at its smallest. Two slides are prepared: one with dry yeast mixed in plain water to show limited activity, and another with yeast in a warm sugar solution, which initiates fermentation and metabolic activity. Under magnification, students can observe budding cells, clustering, and subtle movements that mark the onset of cell division and growth. The contrast between the sleepy, inert cells and their active, bustling counterparts reveals how quickly life responds to the right conditions. For a deeper exploration, AI tools can help analyze the shapes, stages, and behavior of the cells, turning observation into discovery and drawing connections between energy input and cellular awakening.**
The Life of Rot: Monitoring Mold Growth with a Smartphone (BIO-28)
Sensors Used: Camera
What’s Measured: Mold development, surface coverage, and visual changes over time
Description
Decay may seem like an end, but it’s really the beginning of a microbial metropolis. In this experiment, students use a smartphone to observe the growth of mold on food—tracking how fungi colonize, spread, and transform organic matter. Slices of bread, fruit, or agar are placed in sealed containers and left exposed to ambient air, where naturally occurring spores begin their silent takeover. Over several days, students photograph the samples daily, documenting the evolution of texture, color, and size. With magnification or macro photography, fine details emerge: spore structures, color gradients, and the fuzzy networks of hyphae. By comparing growth patterns across different environments—light versus dark, warm versus cool, sealed versus ventilated—students gain insight into how environmental conditions influence microbial activity. It’s a vivid and slightly eerie glimpse into decomposition, microbial ecology, and the role of fungi as nature’s recyclers.**
Microbial Ecology & Biofilms
The Slime Builders: Observing Biofilm Formation on Food Surfaces (BIO-29)
Sensors Used: Camera (optional macro or time-lapse)
What’s Measured: Visual signs of microbial biofilm development
Description
Microbes don’t just drift invisibly through the air—they build. Some bacteria form biofilms: dense, slimy communities that cling to surfaces, resist removal, and represent one of the most successful survival strategies in the microbial world. In this experiment, students investigate how these biofilms form on everyday foods by observing slices of cucumber, lettuce, or boiled rice left exposed in shallow trays with a bit of water.**
Over the course of several days, changes begin to emerge—slippery films on the surface, shifts in color and texture, and the gradual clouding of water. Using a smartphone camera, students can document these transformations, zooming in with a macro lens or recording progress with time-lapse tools. What begins as subtle surface changes soon reveals the structured life of microbial colonies.
This experiment not only makes visible the invisible world of microbial ecosystems but also raises important questions about hygiene, food safety, bacterial resistance, and how even a forgotten vegetable can become a living laboratory.
The Hidden Rain: Capturing Spore Dispersal from Mushrooms (BIO-30)
Sensors Used: Camera
What’s Measured: Pattern and density of fungal spore dispersal
Description
Fungi may not have flowers, but their reproduction is no less remarkable. In this quietly dramatic experiment, students reveal the hidden rain of mushroom spores by capturing spore prints—turning an invisible process into a striking visual display. To begin, a fresh mushroom cap is placed gill-side down on a sheet of white or black paper, chosen to contrast with the expected spore color. The cap is then covered with a bowl or container to block air movement and left undisturbed overnight.**
By morning, the paper holds a delicate imprint: radial patterns that reflect the gill structure beneath the cap, formed entirely by the microscopic spores that have silently fallen. Using a smartphone, students can photograph these prints and analyze features like symmetry, density, and dispersion. Comparing spore prints from different mushroom species or under varying conditions can spark discussions about fungal biology, reproduction strategies, and environmental adaptation.
More than just a science activity, this experiment blends mycology with aesthetics—offering a beautiful and data-rich introduction to the secret life of spores.
Plant Signaling & Sensing
Listening to the Roots: Measuring Soil Moisture with DIY Sensors (BIO-31)
Sensors Used: Soil moisture sensor, optional Bluetooth module or audio jack interface
What’s Measured: Soil water content, drying rate, and plant-water interaction
Description
Water isn’t just essential to life—it’s also a dynamic variable that students can measure directly in the soil. In this experiment, soil becomes a living data source as students use DIY moisture sensors to explore how water moves, evaporates, and supports plant function. A resistive or capacitive sensor, paired with a simple circuit, connects to a smartphone either via Bluetooth, a voltage-to-frequency converter through the audio jack, or even a basic LED or buzzer setup. With the system in place, students can measure how soil moisture levels change after watering, under sunlight versus shade, or at varying depths. These readings can reveal patterns of transpiration, the reach of root zones, and differences in soil composition. The result is a tangible, data-rich investigation that ties together physics, environmental science, and plant physiology—offering a hands-on way to understand the invisible flow of water beneath our feet.**
Can Plants Scream? Measuring Voltage and Sound Responses to Stress (BIO-32)
Sensors Used: Microphone input (for voltage monitoring), ultrasonic microphone (optional)
What’s Measured: Electrical signals and ultrasonic emissions from stressed plants
Description
It may sound like science fiction, but plants under stress can emit detectable electrical and acoustic signals—faint, measurable echoes of their inner state. In this experiment, students investigate whether plants “scream” by exploring two different methods of stress detection. The first involves measuring electrical signals: by attaching simple electrodes, such as foil clips or conductive pads, to a plant’s stem or leaves, students can record rapid voltage shifts when the plant is touched, cut, or begins to dry out. These tiny pulses, amplified through a basic op-amp circuit and fed into a smartphone’s microphone input, become visible through an oscilloscope app—offering a glimpse into plant bioelectricity.**
The second approach focuses on sound, specifically ultrasonic emissions. Some research suggests that plants experiencing drought emit high-frequency clicks caused by cavitation events in the xylem. Using a USB ultrasonic microphone and a frequency analysis app, students can attempt to capture these acoustic signals. Even without ultrasonic tools, a standard smartphone microphone may pick up low-frequency vibrations or other sound changes under stress.
Both approaches raise compelling biological questions: Do all species emit similar signals? Can stress be detected before visual symptoms appear? Could this represent a form of plant communication—or even a primitive nervous system? This experiment turns abstract scientific headlines into something students can test for themselves, blending electronics, acoustics, and plant physiology into a truly interdisciplinary exploration.
Animal Behavior & Bioacoustics
Cameras and Creatures: Observing Animal Motion and Behavior (BIO-33)
Sensors Used: Camera
What’s Measured: Animal movement, foraging behavior, response to stimuli
Description
Animal behavior is biology in motion—subtle, dynamic, and full of meaning. With just a smartphone camera, students can explore the ways creatures move, respond, and interact with their surroundings. This experiment invites observation of everything from the winding path of an ant to the eager reactions of a household pet. Whether in a controlled setting or a natural environment, students can record video footage of animals as they forage, explore, or respond to changes. By using basic video analysis tools, they can measure speed, track movement patterns, and even construct simple maps of foraging paths or obstacle navigation.**
To explore behavioral responses more deeply, students might introduce a stimulus such as food or light at varying distances or angles, then observe how the animal alters its approach. Does it choose the shortest path? Hesitate in low light? These everyday observations become entry points into the study of ethology and sensory biology, raising questions about perception, decision-making, and adaptation. With nothing more than a phone and patience, the rich language of animal behavior becomes visible, measurable, and full of insight.
Echoes of the Wild: Analyzing Birdsong and Insect Calls (BIO-34)
Sensors Used: Microphone
What’s Measured: Frequency patterns, species-specific calls, bioacoustic variation
Description
Nature hums with hidden messages—trills, chirps, croaks, and clicks that fill the air with meaning. This experiment brings students into the world of bioacoustics, where sound becomes a language to study and decode. With just a smartphone and a sound analysis app, students can record the calls of birds at dawn, crickets at dusk, or frogs along a pond’s edge. These recordings, once loaded into a spectrogram or FFT visualization tool, reveal intricate frequency patterns, rhythms, and structures that often differ between species—and sometimes even between individuals.**
By comparing recordings made at different times of day, in various weather conditions, or in quiet versus noisy environments, students can observe how animal communication shifts in response to ecological and social pressures. Beyond appreciating the beauty of birdsong, this experiment dives into the science of how animals use sound for territory defense, mating, alarm, and navigation. It’s a gentle but powerful entry into wildlife monitoring, acoustic ecology, and the universal importance of voice in the natural world.