We high school physics teachers tend to associate the right-hand rules with electromagnetism. As a student, my first encounter with a right-hand rule was when I was introduced to the magnetic field produced by the electric current in a long, straight wire: if you point the thumb of your right hand in the direction of the conventional current and imagine grasping the wire with your hand, your fingers wrap around the wire in a way that is analogous to the magnetic field that circulates around the wire.
I only later discovered that this same rule can be applied to rotational quantities such as angular velocity and angular momentum. The topic of rotation has become more important in AP physics when the program was updated from the older Physics B program. Strictly speaking, AP Physics 1 does not include the use of the right hand rule for rotation, but I have found that introducing it actually helps solidify student understanding of angular vectors.
Describing the direction of rotation as being clockwise or counterclockwise is helpful only if all parties involved have a common point of view, which is ideally along the axis of rotation. As with left and right, clockwise and counterclockwise depend on your point of view. This is why it is often preferable to describe translational motion in terms of north, south, east, west, up, and down, or with respect to a defined x-y-z coordinate system; directions can be communicated unambiguously, provided that everybody uses the same coordinate system.
It is precisely for this reason that the right hand rule can (and should) be used for rotational motion. Consider the hands of an analog clock. Assuming that the clock is a typical one, it will have hands that turn “clockwise” when viewed from the “usual” point of view, but if the clock had a transparent back and you were to view it from the back you would see the hands turning “counterclockwise!” The observed direction of rotation (clockwise or counterclockwise) depends on the observer’s point of view.
Instead of using clockwise and counterclockwise, we can describe the direction of rotation with a right hand rule: if you curl the fingers of your right hand around with the direction of the rotational motion, your thumb will point in the direction of rotation, which will be along the axis of rotation. Applying this to the above we find that when viewing a clock from the front, the rotation of the hands is three dimensionally into the clock (away from the observer), and when viewing a clock from the back side, the rotation of the hands is three dimensionally out of the clock (toward the observer). If two people view a transparent clock at the same time but one observes it from the front while the other observes it from the back (i.e. the clock is between the two people who are facing each other), they will disagree on which way the hands turn (clockwise or counterclockwise) but will agree on this direction if both use the right hand rule convention to describe the direction of the rotational motion – both observers will agree that it is directed toward the person viewing the back side of the clock.
When first learning about the right hand rule, students are often initially confused, with many students failing to grasp why such a rule is even useful in the first place. Before introducing the right hand rule I like to begin by holding an object such as a meter stick while standing at the front of the classroom. I then rotate the meter stick through its center so that the students claim that it is rotating “clockwise” when asked. Being careful to keep the rotational motion as constant as possible, I then walk to the back of the room. It’s important that the students see that at no point did I stop the rotation of the meter stick – it is still turning the same way as before, and yet at some point each student finds that they must turn around in order to continue to see it. Many students are astonished to see that the meter stick is now rotating counter clockwise from their (now reversed) point of view. This helps establish the need for a better way to describe rotation.
I then introduce the right hand rule and go through a couple of examples. Traditionally, this would have been the end of it, but last year I was able to take advantage of my newly acquired PASCO Smart Cart, which has a wireless 3-axis gyroscope (i.e. rotational sensor). The coordinate system is fixed with respect to the cart, and is printed on the cart itself, but I like to make this more visible by attaching cardboard cutout vectors onto the cart which make the axes more visible to the students while I hold the cart up for them to see. I then set up a projected display of the angular velocity of the cart along each axis simultaneously. I then ask the students how I must turn the cart in order to get a desired rotation of my choosing (i.e. ±x, ±y, and ±z).
I really like how the carts, along with the live display of the 3 angular velocity components make the admittedly abstract right hand rule so much more concrete. Seeing the display agree with our predictions makes it so much more real and is much, much better than me merely saying “trust me.” I have found that introducing and using this right hand rule with rotation has made using this same rule much more natural when using it to later relate the direction of current flow and the magnetic field.
Reposted from the NSTA Blog, original article can be found here.
The PASCO Wireless Spectrometer
Simply put, constructivism is a theory of knowledge that argues that humans generate knowledge and meaning from an interaction between their experiences and their ideas. So it follows that nothing is can be more constructivist than exploring the theoretical with real-time tools that measure the invisible. And the PASCO Wireless Spectrometeris just such a tool.
One of the most amazing things about the PASCO Wireless Spectrometer is that it does exactly what you would want it to do; show you the invisible with ease, simplicity, and leave behind a useful digital paper trail of graphs and charts. Although the main purpose of the PASCO Wireless Spectrometer was “specifically designed for introductory spectroscopy experiments” it actually goes farther than that. Much farther. Much much farther!
This trio of teachers, two from China and one from Mongolia have limited English speaking skills, but instantly understood the iPad app and PASCO Wireless Spectrometer. Seems that light is also a universal language.
The physics and electronics behind the PASCO Wireless Spectrometer are straight forward. The output is clear and obvious. And the mobility aspect is unprecedented. In other words, it does what it should how it should. Amazing enough on its own, but in true paradigm shifting fashion the PASCO Wireless Spectrometer presents the invisible world of visible light in the magical cartoon chart we’ve seen only in static textbooks for most of our lives. It’s as if the dinosaur skeletons in dusty museums suddenly came alive and reacted to the world.
Visible light, or the light our human eyes sense and convert to electrical impulses to our brains, only encompass a tiny fraction of the electromagnetic spectrum. Wavelengths between 390-700 nanometers, or from the short blue/violet waves to the longer orange/red ones with green and yellow in the middle. Infrared waves are just a little too long for us to see, and ultraviolet ones are a little too short. Even longer are radio waves, and even shorter are x-rays. The PASCO Wireless Spectrometer has a range of 380 to 950 nanometers meaning it can “see” a little into the ultraviolet and a lot into the infrared.
An ultraviolet light spikes the graph just outside the shortest wavelength we can see with our eyes.
Where this all comes together is that when the PASCO Wireless Spectrometer and various light sources are manipulated with our hands, the extended visible spectrum becomes something we can explore with the same cognitive dexterity as the microscope affords us in biology. When used in the classroom for demonstrations and explorations, the PASCO Wireless Spectrometer literally lets “humans generate knowledge and meaning from an interaction between their experiences and their ideas.” So yes, the PASCO Wireless Spectrometer is the epitome of constructivist theory into educational practice.
Although Isaac Newton is credited with discovering the inner workings of visible light back in the latter 1600s, the basic concept behind a rainbow was suggested by Roger Bacon 400 years earlier who in turn drew upon the works of Claudius Ptolemy a millennium before, and even Aristotle another 300 years before that.
As a quick digression here, the Newtonian physics behind the PASCO Wireless Spectrometer has roots much more than five times deeper into the past than Mr. Newton’s distance in time is from us right now. Sorry to go all Einstein on you, but the individual colors of visible light that Newton coaxed out of sunlight with only a glass triangle, and then reassembled with nothing more than a companion prism was like yesterday. Yet the attempts to explain the phenomena were first floated last week.
And now to think that within the palm of a student’s hand and the screen of their iPad is a gift of knowledge as great as the discovery itself. A stretch? Perhaps, but unless a scientific concept can be truly understood to the point one can make personal meaning out of the discovery, memorized facts are little more than coins used to buy grades.
Technically speaking, the PASCO Wireless Spectrometer is a battery operated spectrometer that uses Bluetooth wireless or a USB wire in order to communicate with a computing device running the necessary software. With its own built-in LED-boosted tungsten light source and three nanometer resolution, the PASCO Wireless Spectrometer provides an exceptional tool for traditional experimentation with pl
enty of room left over to inspect rarely explored specimens of light scattered throughout our lives.
The operation of PASCO’s unassuming black brick puts the power of spectrometry into the hands of grade school students and Ph.D. candidates alike. While maybe not the most durable block in the scientific toy box, the PASCO Wireless Spectrometer does offer a level of simplicity (when desired) as easy to use as glass prism and sunlight. Of course you can do much more with the PASCO Wireless Spectrometer, but you don’t have to in order to get your money’s worth. This spectrometer does so much so well so easily that it literally rewrites lesson plans just by walking into the classroom.
On a higher level, the PASCO Wireless Spectrometer can be used in chemical experiments of intensity, absorbance, transmittance and fluorescence all while using a device that, according to PASCO, has light pass through the solution and a diffraction grating and then a CCD array detects the light for collection and analysis. Sounds simple enough just like a digital prism should. Except this one gives about nine hours of service per battery charge.
In the off chance that the battery fails, it is user-replaceable. in the off chance the light burns out, it is user-replaceable. And in the likely chance that liquid from a cuvette spills into the holder, a drain hole limits the damage, and cleaning the holder is user-serviceable with a cotton swab and deionized water.
A portable studio light is used to provide a background of predictable photons in order to explore the absorbance properties of various types of matter including sunglasses, polarizers, fabric, and theater lighting filters.
The PASCO Wireless Spectrometer must interface with a computer or tablet. Both Mac and Windows are supported as is iOS and Android.
PASCO also suggests using the Wireless Spectrometer for the following popular labs:
Absorbance and transmittance spectra
Beer’s Law: concentration and absorbance
Photosynthesis with DPIP
Absorption spectra of plant pigments
Concentration of proteins in solution
Rate of enzyme-catalyzed reactions
Growth of cell cultures
Light intensity across the visible spectrum
Emission spectra of light sources
Match known spectra with references
And PASCO also provides several sample labs for plug-and-play directly into the chemistry classroom. But the really exciting plug-and-play option is the accessory fiber optic probe. With no more effort than sliding a faux cuvette into the receiving slot on the spectrometer, a meter-long fiber cord moves a directional sensor out into the wild where it can capture photons from all kinds critters. Some of my favorite animals include UV lights, filtered lightbulbs, various school lighting sources, sunlight though sunglasses, polarizers, and pretty much any LED flashlight I can find, especially the really good ones.
Although the screen output from the PASCO Wireless Spectrometer’s software is a graphical representation of a physical property, it takes almost no mental gymnastics to understand the changes to the graph once your mind is oriented to the display. The color-coded background and gesture-ready scaling provides an exceptionally smooth relationship with the data to the point all the hardware and software disappear leaving only the experiment and the results. And in my book, that kind of invisibility is the true measure of success with a teaching product.
When teaching the next generation about the important discoveries of the past generations, we have an obligation to use the most powerful educational tools possible. The PASCO Wireless Spectrometer is truly 100% pure constructivism-in-a-box. It turns experiences and ideas into personal meaning. Battery included and no wires necessary.
Coming Fall 2019! Free Upgrade for Capstone 1.x users!
Updated with new tools! Designed specifically to collect, display and analyze data in physics and engineering labs.
What’s New in Capstone 2
Reinforce circuit concepts and tackle student misconceptions using circuit visualization. Combine real-world circuits with simulations, animation, and live measurements.
With the Circuits Emulation tool in Capstone 2, you can:
Construct and modify circuits
Show conventional current and electron flow animation
Animate circuits with live sensor data
Drag components out from the components list. Rotate components, and connect pieces together by drawing wires.
This is how science is actually done.
You never take only one run in science. You take multiple runs, and calculate averages. Next, you vary a parameter while holding the other constant; again, taking more runs and calculating averages. Most software data tables don’t actually allow this to be done easily.
The Capstone Trails table was created for how data is collected in the science lab, and allows for the kind of analysis students need to perform.
Organize your data to easily define physical relationships.
Plot derived values
Using the simple pendulum lab as an example, students will time a simple pendulum under various conditions. They will vary the mass, length, and starting angle. The Capstone Trials Table allows you to vary and keep track of experimental parameters between trials, and runs taken in each trial. You can also keep track of statistics for averaged runs and experimental error.
Helps students develop computational thinking skills
Physics educators want more experimental control and programming access to all PASCO interfaces and sensors. Students need tools to develop creative programming and problem-solving skills in science. Blockly coding has been built into Capstone 2, giving teachers and students the tools they need to develop these skills.
Graph Pop-Up Tools
Now, whenever tools are activated, the most common actions will be easily accessible on the graph. The pop-up tools allow for easy access to tool features and options.
PASCO Capstone allows users to quickly layout custom pages, automatically recognizes sensors when connected, has a powerful set of analysis tools and much, much more.
PASCO Capstone was built from the ground up to be the most powerful and flexible option for physics and engineering applications.
Can be used with all current and legacy PASCO USB interfaces.
Works with all PASCO sensors — ScienceWorkshop, PASPORT, and Wireless.
Completely customizable lab pages
Multiple displays including graphs, tables, oscilloscope, bar meters, FFT and more
Capstone includes a very powerful video analysis feature which can be used for comprehensive analysis of moving objects as well as to improve understanding. Short video clips from your smartphone can be easily imported and analysed with a range of tools. The movement of objects with a high contrast to a uniform background can be automatically tracked by the software.
A ball will be thrown in a parabolic arc and various tools will be used to analyze the motion. Note that the vertical and horizontal axes have been marked and a distance of 4.00 m has been measured. This will enable the software to translate from pixels to m:
As part of the analysis, the position of the ball in each frame is marked and the result is as shown below:
It is now possible to have the software generate various graphs such as position vs time and velocity vs time.
A graph of vertical position vs time is as shown below:
A graph of horizontal position vs time yields the following:
A graph of the vertical component of velocity vs time yields the following result:
Capstone also includes tools that improve understanding. For example, in the screen below, the vertical and horizontal components of velocity are shown for the ball as it flies through the air.
To make the display less cluttered and less confusing it is possible to mark the vectors at an interval other than every frame. Below the vectors are shown every third frame:
It is also possible to have a single vertical vector and a single horizontal vector appear and move with the ball as it goes through the air.
It is also possible to show the acceleration vector as shown below:
The fact that a few vectors do not point directly down is likely due to minor errors made when marking the position of the ball in various frames with a mouse.
It was the shot heard across Canada. There were a lot of factors that made Kawhi’s buzzer beating basket so remarkable. Aside from there being no time left on the clock and the weight of a sport’s nation on his shoulders, Kawhi had to overcome the backward momentum that is inherent in a ‘fadeaway’. The purpose of a fadeway is to create space between the shooter and defender(s), which was a necessity for Kawhi as there were several seriously tall 76ers trying to screen his shot.
Over-coming the fadeway’s backwards momentum is no easy feat as it requires players to quickly calibrate in their minds the additional force that is required to successfully sink a basket, which for most mere mortals is not intuitive. The shot is so challenging that only a handful of NBA basketball players have been able to reliably make this shot; and we’re talking the great players such as Michael Jordan, Lebron James, Kobe Bryant and of course Kawhi Leonard.
The video below provides an extreme example of backwards momentum with a soccer ball shot from the back of a truck
Investigating Kawhi Leonard’s shot in the lab
In addition to backwards momentum there were many additional physical factors at play such as the angle of the shot and gravity. Investigating all these forces in a single activity would not be practical. Fortunately most of these forces can be isolated and explored in the lab using PASCO sensors, software and/or equipment.
Exploring The fadeaway’s negative momentum using PASCO
PASCO offers an intriguing and affordable solution to model the dramatic effect of a fadeaway’s negative momentum on projectile distance. PASCO’s mini launcher will consistently launch projectile balls the same horizontal distance for a set angle, assuming that the launcher is stationary. If however, the launcher is placed on PASCO’s frictionless cart, the force of pulling the trigger will cause the cart to move backwards at a velocity that can be measured using the motion sensor. Students will be surprised to see that even though the cart travels just a few centimeters, the overall projectile distance is significantly reduced. This can be a very simple demonstration or an in-depth quantitative analysis that factors in the projectiles initial angle and velocity, the time of flight and even the k-constant of the spring.
Other Forces Affecting a Basketball Shot
Momentum and Explosions
When a basketball player takes a jump shot (as with a fadeway), the player and the ball could be viewed as 2-object linear system if you ignore other outside forces such as gravity. What’s interesting, and perhaps not apparent to many students, is that the basketball will exert an equivalent force to the player as the player is exerting on the basketball (Newton’s 3rd Law). Of course because of the very significant inertia (mass) difference between the two objects, the basketball will accelerate at a much fast rate than the player. The player however will experience some acceleration in the opposite direction to that of the basketball.
Using Smart Carts to explore Momentum and Explosions (Free Lab)
The Wireless Smart Carts are equipped with an exploding plunger. Multiple 250g bars can be added to one cart to skew the masses. The velocities of both carts are measured using the cart’s internal position sensors enabling students to determine that momentum is conserved in a linear exploding system.
The player’s force on the basketball will be equal to the opposing force of the basketball onto the player. Of course most students will consider this a ridiculous proposition until they prove this for themselves.
Using Smart Carts to explore Newton’s Third Law
There are several ways the carts can be used. The simplest activity is for two students to have a tug-of-war using the internal force sensors of two Smart Carts and an elastic band as depicted in the image. The equal but opposite forces will be confirmed, however in relation to a basketball player taking a shot, it has some shortcomings as the forces are pulling as oppose to pushing.
An equally simple activity, and one more relevant to the basketball shot scenario, is to collide two Smart Carts (with magnetic bumpers attached to their force sensors). As both carts have equivalent masses, students may not be surprised to see the impact forces are identical. However, what will probably surprise your students, are the force measurements that occur during a collision when one cart is weighed down with one or more 250g masses. Using their intuition, most students will speculate that one of the carts will experience a much greater force than the other. Of course, Newton’s 3rd Law will triumph and the forces will be identical.
What goes up must come down. This is true of course for all earth bound objects (including basketballs) due to the ever present force of gravity. Without gravity the trajectory of a basketball player’s shot would be straight to the ceiling of the arena, where most of the fans would be viewing the game.
Exploring the accelerating force of gravity using the Motion sensor
PASCO offers several technologies and techniques for measuring gravity including the Wireless Smart Gate and Picket Fence and the new Freefall apparatus. Both of these techniques are accurate and precise means to measure gravity. A third technique and one more appropriate for relating to a basketball shot is to measure the position of a vertically tossed ball and then have the software derive an acceleration graph from this data. Statistics, including the Mean of the acceleration plot can be calculated by the software for the period when the ball was in freefall as shown in the graph.
SPARKvue 4.0 is here to make data collection and analysis even easier, whether you use Chromebooks, Computers, iPads & iPhones, Android devices, or our standalone dataloggers, the SPARK LX and SPARK LXi.
Watch this video for a quick run-through of all the new features.
Improvements included in version 4.0
A new menu for frequently used features
A revamped Welcome Screen (see below)
Share experiment files directly to cloud services such as Google Drive or OneDrive.
Show only the most recent run data by default.
Calibrate and configure sensors through the new hardware setup features.
A new Live Data Bar has been created for experiments.
The new Welcome Screen gets you up and running even faster.
About the new Welcome Screen
Choose the type of experiment you want to perform:
When using Sensor Data, SPARKvue will also guide you to a configuration panel, help you select measurements for display, and let you choose from a range of templates.
You can also build your own experiments, open a saved experiment, or open any of the many PASCO built activities.
Your one-time purchase of a license or download of the app includes free updates. SPARKvue software is constantly being refined with additional features, streamlined processes, and support for our innovative new products. Much of that improvement comes directly from feedback provided by educators.
Award-winning, cross-platform data collection and analysis software
Data collection and analysis is an integral part of any science investigation. Whether graphing manually-entered data, collecting real-time data from a sensor, or remotely logging data, SPARKvue software helps you and your students address important science and engineering practices in your labs.
Easy-to-use and yet powerful, SPARKvue’s collaborative features make this application ideal for use in and out of the science classroom or lab.
Data Collection & Display
Live Data Bar
Multiple plot areas
Graph or plot user entered data
Weather Dashboard (when used with the Wireless Weather Sensor with GPS)
Select a region
Smart tool (coordinates and deltas)
Add a y-axis or a new plot area
Designed for Science Learning
Convenient annotation, snapshot and electronic journaling are among the features supporting peer dialogue, classroom presentations, and assessment.
Create and export electronic student lab journals.
Integrated with cloud-based file-sharing services such as Google Drive, Dropbox and more.
The same user experience across:
Our standalone SPARK LX dataloggers
Compatibility at a glance
Click on your device or devices to see SPARKvue compatibility.
Windows 7 SP1 or later
Mac OS X v 10.10 or later
1 GHz Processor
An Intel Core 2 Duo, Corei3, Core i5, Core i7 or Xeon Processor
2 GB RAM
2 GB RAM
435 MB Free Disk Space (255 MB for SPARKvue, 74 MB for Common Files, and 105 MB for Experiments)
200 MB Free Disk Space (Application Bundle)
1024 X 768 or greater resolution
1024 X 768 or greater resolution
Chromebook running ChromeOS 57 or later, USB and Bluetooth
Requires iOS 9 or later, compatible with iPhone, iPad, and iPod touch.
Android 4.4 or later.
The new Welcome Screen.
Graph data from a sensor and see the results in real time.
A Bar Graph used to investigate absorbance
Boyle’s Law using both manually entered data and sensor data
The new Weather dashboard to monitor atmospheric conditions.
Hello World! My name is Maayan, and I am another co-op student at AYVA. I’m currently studying biochemistry at the University of Guelph, which is how I ended up on the AYVA Team. A bit more about me: I do not have any cute pets, but I do have two younger brothers. I’m interested in science, especially all the cool discoveries that can be made to improve the human condition. Outer space is rad. I can talk about Mars colonies for hours on end.
How did I get into science?
As a wonderfully sweet little child, I frequently stole my brothers’ toys. I built Lego castles, controlled toy cars, and appropriated (stole) puzzles by the box. I liked building things, and I liked breaking things down to see how they worked. As I continued to grow into an adolescent, I enjoyed reading science fiction, enough to finish all the books my school library had.
Eventually, as I skipped on through life, I was assigned to do a school project on an important Canadian. I chose Julie Payette, an astronaut (and currently the Governor-General), and my interest was born. It was amazing to me that people had gone to the moon, and now different countries were collaborating on the International Space Station for scientific research. For the first time, I felt that people could come together for a cause to further humanity. The five-dollar bill is still my favorite: it has the Canadarm2 and the astronaut on it. To this day, I smile whenever I see one.
In high school I realized that astronauts couldn’t have gotten to space without a team of people down on earth who helped solve problems, and just because their jobs were less flashy (and got less camera time) it did not mean that they were any less important. Anyway, I liked biology (humans!) and enjoyed learning chemistry (and about the universe). I couldn’t decide which one I liked better, so biochemistry is the major I chose. No one seemed to be offering xenobiology or astrobiology courses at the time, but I hope someday they will.
Back to the blog, I will be writing a few articles on teaching science through inquiry. This is important for future STEM-ists since teaching STEM is only a step before understanding STEM. After all, every inventor, scientist, engineer, mathematician, technologist, and astronaut started as a student.
Measuring Carbon Dioxide (CO2) has many applications in the classroom and with the latest advances in technology is easier and more affordable than ever before. Here’s a quick look at some of the cool things you can do with the new Wireless CO2 Sensor!
1. Monitor Air Quality
An engaging way to introduce students to the sensor is to use the “closed” environment that you already have access to – your classroom or lab. This is also a great opportunity to use the data logging capabilities of the sensor. Find a central place in the room to place the sensor, ideally suspended above students heads where they can’t exhale onto the sensor. Place the sensor into logging mode, and collect 8-10hrs of data (Figure 1a). Depending on the student density in your room, HVAC, how closed the environment is, you should be able to see fluctuations in the CO2 levels that correspond to the class schedule because all of those students are busy breaking down glucose and producing CO2.
Figure 1a. Data from sensor logging over a school day.
Students can repeat this test in other locations such as the cafeteria, greenhouse, bathrooms, etc. While there are conflicting standards generally a CO2 concentration of <1,000ppm is desirable and >3,500ppm people will begin to experience physiological effects. Many modern HVAC systems even have their own sensors that will cycle the air to maintain CO2 levels <1,500ppm you can probably tell from the data if you your school or lab has one!
Figure 1b. Data with bell schedule overlaid
2. Investigate Cellular Respiration
With the included sample bottle students’ can use invertebrates, germinating seeds, or other small organisms to quickly collect respiration data. Variation in environmental factors like light or temperature provide easy extensions as well as germination time, species comparisons, body mass, activity level, etc.
Figure 2. Respiration of Germinating Seeds
Extending this setup the sensor can be used with bacterial or yeast solutions, even aquatic species by measuring the gas concentration in the headspace of the container.
Figure 3. Headspace Measurement above a liquid
While a smaller chamber will yield faster results (gas concentration will change faster) sometimes a bigger chamber is needed to study larger organisms or when modeling ecosystems. This is where the wireless design is particularly helpful, the sensor can easily be placed inside any container along with the organism being studied – without any modifications. If you need to run the sensor for longer than about 18hrs, connect it to an external USB power pack or source and the sensor can continue working.
Figure 4. Sensor inside a larger food storage container
3. Investigate Photosynthesis
To get great photosynthesis data you just need a fresh dark green leaf, the sensor, and the sample bottle. Put the leaf in the bottle, cap it with the sensor and start data collection! Using the sample bottle and a fresh leaf ensures a quick response – data runs of 5-10min! Light vs. Dark and wavelength are simple and relevant manipulations for students to conduct.
Figure 5. Photosynthesis using a single Epipremnum sp. Leaf with no filter, blue filter, red, and green applied. Plants exposed to full spectrum CFL bulb for 10min runs.
CO2 Rate (ppm/min)
Light (no filter)
Dark (tinfoil wrapped)
Table 1. Summary of change in rate found from each run of data.
And more ideas (than I have time to test): Light intensity, impact of temperature, herbivory, time of day, herbicide impact, stomata density, C3/C4/CAM Plant comparison, CO2 Concentration
4. Measure Carbon Flux in the Field
In some cases lab experiments aren’t feasible or desirable. It’s easy to take the sensor into the field using a cut bottle, bell jar, or plastic bag to isolate a plant or patch of soil for analysis without disturbing the environment. Firmly press the container into the substrate to create a tight seal and begin collecting data. Students can easily compare different ecosystems to determine if they are a net carbon producer or consumer under conditions. This technique can be repeated in different conditions, times of the day or year to compare results.
Figure 6. Cut bottle with sensor place over patch of turf
This same technique combined with the concept of measuring a headspace over a liquid to determine the gas exchange can be used to monitor carbon flux in an aquatic ecosystem. Securing the sensor with a float (or to a fix object) to protect it creates the airspace needed to measure above the water. Collect data for the day to see how a body of water is exchanging carbon with the atmosphere.
Figure 7. Using a float and cut bottle to create an airspace and measure carbon exchange
5. Monitor Respiration of Soil Microbes and Decomposers
To streamline the sample collection and measurement of soil samples students can use a section of PVC to collect a consistent volume of substrate and make the measurement in the same chamber. A 6-8in (15-20cm) section of pipe with an inner diameter of ~1.125” (3cm) can be easily pounded into the ground a specified depth to collect the sample. Seal the end of the pipe with some parafilm or plastic wrap and collect the data.
Figure 8. Sensor in PVC tube with marking for soil sample depth, clear PVC used to demonstrate
Data collection can take place in the field or lab and is easily extended for inquiry. Students can treat the samples with pH buffers, water, drying, salt, pesticides, or other chemicals of interest to determine the impact on microbe respiration.
6. Measure Human Respiration
Using a drinking straw and a 1gal (4L) ziplock® bag its easy to capture human respiration data. Here’s a video comparing breath hold time. This same procedure can be used to test other variables, before and after exercise, time of day, etc.
7. Dissolved CO2 in situ
With Dissolved CO2 Sleeve students can monitor CO2 in an aquatic environment. The Teflon® material is permeable to CO2 molecules but not to water, creating a much smaller headspace around the sensor with a better response time. While the CO2 is not dissolved when its measured this approach has been validated and tracks with other indicators such as pH (Johnson et al 2010). Â This approach works well in the field and in the lab for photosynthesis and respiration experiments. Below is a picture and some data we collected during betta testing!
Johnson, M. S., Billett, M. F., Dinsmore, K. J., Wallin, M. , Dyson, K. E. and Jassal, R. S. (2010), Direct and continuous measurement of dissolved carbon dioxide in freshwater aquatic systems – method and applications. Ecohydrol., 3: 68-78. doi:10.1002/eco.95