With the shift toward three-dimensional teaching and learning that the Next Generation Science Standards requires, the Crosscutting Concept of Modeling has become a major focus of my instruction.  I use a process that involves revisiting the same model at least three times in a unit to support students’ growth in this area.

Each unit starts with a puzzling phenomenon that can be fully explained by the concepts covered in the unit. Students observe the phenomenon in a video clip or demonstration, then draw a concrete model of what they observed. For more complex, multi-step phenomena, I give them basic drawings of the areas to focus on; they can add details to these drawings.

Once they have a complete drawing, they label and describe what they think is happening and why. These initial models are often basic and full of misconceptions. I find this very informative because I see exactly what they know and understand at the start of the unit.

Students have an opportunity to give and receive feedback using sentence stems on their initial models.  Each student is given stickynotes and asked to provide at least one positive and one constructive comment for three different students. Examples of positive sentence stems are “I like how you…” and “When you did _____, I could really understand it.” Some constructive feedback stems are “The part about ____ is a bit unclear”  and “You could…” or “Have you thought about including …?”

Over time, the students learned how to use the feedback they gave to others to improve their own models. After the feedback round, students were able to add to their own models before turning them in.

At the halfway point of the unit (about 5–10 days of instruction), students revise their initial models using a writing tool in a different color. They are encouraged to cross out things they now think are incorrect and add new things they’ve learned. They must also add to their written description of what is happening at each step. I encourage them to work with partners/small groups to enhance their current understandings.

At the end of the unit, they are given a blank copy of the model and must repeat the whole process once again. At this point, they should be able to fully explain the phenomenon, clearly showing what they learned from the unit. 

With a range of students from Level 1 English language learners to Highly Capable students, differentiation is needed so all students will succeed with modeling. The primary modification I use is providing a word bank for all but the Honors-level classes. This helps students remember to include all of the necessary parts.  Directions with descriptions of all the steps help them as well. 

I allow students needing the most support to simply label the drawings using arrows and the word bank, rather than writing a paragraph. They are still able to show their understanding of the concepts without getting bogged down in the language.

With the multiple model iterations of the complex guiding phenomena, I am able to assess students’ understanding of the unit and how their understanding changes over time. The mid-unit revisit allows students to be more cognizant of how their own understandings have changed over time.

I also use other models throughout my units. The most common one is smaller phenomena related to the larger one. I often use these as warm-ups, and they all help build understanding of the guiding phenomena. Students will draw what they see and describe what is happening.

For the Electric and Magnetic Fields unit, the guiding phenomenon was a magnetic hourglass. To fully explain why the “sand” behaved the way it did, students needed to incorporate information from the previous units, as well as the current one. Throughout the unit, I played video clips centered around the Performance Expectations of MS-PS2-3 and MS-PS2-5. With these clips, I asked students to make a simple drawing with labels of what they observed, then briefly describe why the materials behaved the way they did.

For the Energy Unit, I taught students how to use Google Sheets to do energy calculations as they entered the data and how to use that data to create graphs modeling the relationships among mass/acceleration/force/energy. They were able to manipulate the data without obsessing about the calculations. This made seeing the relationships easier for them.

The most important part of Modeling for me is to make their use very explicit to the students. Usually students think models are things like 3-D scale models of cars or trains. By showing them that models can be drawings, graphs, or equations, they are able to use modeling as a powerful tool in their own inquiry.

Erinn Olson is a middle school science teacher in the Peninsula School District in Gig Harbor, Washington. She previously taught middle school math and science at Mountain View Middle School in Bremerton, Washington, where her activities included teaching Project Lead the Way, working on the regional science and math leadership teams for  10 years, and serving as the school lead for Common Core Math and implementation lead for the NGSS. She also serves as a leader for the Boy Scouts of America at Cub, Troop, and District Levels. Olson grew up in Salem, Oregon, and holds a Bachelor of Science degree in behavioral science and a Masters of Arts degree in education from Oregon State University.

This article was featured in the August issue of Next Gen Navigator, a monthly e-newsletter from NSTA delivering information, insights, resources, and professional learning opportunities for science educators by science educators on the Next Generation Science Standards and three-dimensional instruction.  Click here to sign up to receive the Navigator every month.

Visit NSTA’s NGSS@NSTA Hub for hundreds of vetted classroom resources, professional learning opportunities, publications, ebooks and more; connect with your teacher colleagues on the NGSS listservs (members can sign up here); and join us for discussions around NGSS at an upcoming conference.

The mission of NSTA is to promote excellence and innovation in science teaching and learning for all.

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2018 Area Conferences

• Reno, October 11–13
• National Harbor (MD), November 15–17
• Charlotte, Nov. 29-Dec. 1

2019 National Conference

• St. Louis, April 11-14, 2019

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This week in education news, the Girl Scouts have added 30 new badges in STEM to encourage more female involvement; back-to-school spending will hit $82.8 billion for K-12 and college combined, and more teachers are digging into their wallets; and meet astrophysicist – and NSTA President-elect—Dennis Schatz.

Girl Scouts Launch New STEM Badges

The Girl Scouts have added 30 new badges in science, technology and engineering to encourage more female involvement in STEM. Girl Scouts CEO Sylvia Acevedo joins the ‘Power Lunch’ team to discuss how the non-traditional activities will help girls adapt to a changing world. Read the article featured on CNBC.com.

Teachers Must Budget For Hundreds Of Dollars In School Supplies

Kids love it, parents may dread it, but one thing’s certain: The annual school shopping ritual is a smack to the wallet every year. This year, back-to-school spending will hit $82.8 billion for K-12 and college combined, according to the National Retail Federation’s annual survey. That’s almost as high as last year’s $83.6 billion. Read the article featured on CNBC.com.

Working Geek: A Star In Science Ed, Astrophysicist Dennis Schatz Wants To Expand Minds

Schatz is a solar astrophysicist by training, has written 25 science books for kids and last year Asteroid 25232 was renamed Asteroid Schatz by the International Astronomical Union’s Minor Planet Center in honor of his dedication to science education. He’s worked for the Science Center for four decades. Read the article featured on GeekWire.com.

1st Of Christa McAuliffe’s Lost Lessons Released From Space

The first of Christa McAuliffe’s lost lessons finally was released from space Tuesday, 32 years after she died aboard Challenger. Read the article featured in Education Week.

8 Apps You Should Check Out Before School Starts

Check out this list of apps, ranging from kindergarten through high school and touching on topics such as STEM, history, and vocabulary. Read the article featured in eSchool News.

Stay tuned for next week’s top education news stories.

The Communication, Legislative & Public Affairs (CLPA) team strives to keep NSTA members, teachers, science education leaders, and the general public informed about NSTA programs, products, and services and key science education issues and legislation. In the association’s role as the national voice for science education, its CLPA team actively promotes NSTA’s positions on science education issues and communicates key NSTA messages to essential audiences.

The mission of NSTA is to promote excellence and innovation in science teaching and learning for all.

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I have accumulated a large number of the freezer gel packs from a meal service. I’d like to find a way to use them in a classroom activity.
—P., Georgia

The best thing about these freezer packs is that they provide a constant that will help your class design and conduct a lot of experiments. Reusing these in your classroom is also a great environmental message.

A few ideas for experiments :

• Engineer the best picnic cooler. (Save styrofoam boxes and pellets from shipments you have received).
• Determine the optimum place to put a freezer pack in a standard cooler.
• What conditions speed up/slow down warming or cooling? Correlate the data with ambient temperature.
• Investigate the heat conductivity of different solids and liquids. Put the packs in ziplock bags and immerse them in oily/messy liquids.
• Surface area experiments: curl them up, lay them flat, stack them vertically/horizontally, spread them out. Relate this information to physical science, chemistry and even biology.
• The contents of freezer packs are non-toxic. Open them up and do carbohydrate, lipid, protein, and other chemical tests on the contents.
• Place them on different parts of the hands and arms to create a cold sensitivity map.

As useful tools:

• Keep them in the freezer to use instead of ice cubes for chemistry or biology activities.
• Putting live insects in a freezer for a few minutes will slow them down. Place the gel packs under the insects to keep them cool while observing them with microscopes or magnifying glasses.

Hope this helps!

Photo credit: By Dhenning2005, aka Dave Henning [Public domain], from Wikimedia Commons

Sometimes the discovery of materials on a play area inspires children’s exploration and use of the NGSS science and engineering practices. 

In this example a long length of bark from a tree branch became a trough for investigating water flow.

At first the 5 year old simply put the curved length of bark at an incline to make a path for water which was being used elsewhere in the outdoor play area. Her choice was likely informed by her prior experiences with balls and ramps, and in water play. In her actions she is planning and carrying out an investigation, asking what will happen to the water as it moved from a container onto the bark trough and trying to solve the problem of designing a system to carry water. A teacher supported her by standing nearby and watching intently, showing interest, and asking a few open-ended questions. “Where is the water going?” “What might happen if you drop the water from a higher up or a lower down?”

The child poured water into the trough at the top, watching it flow down and soak into the sand. Then she added another container at the bottom to try to catch the water. Additional children joined in. Repeatedly pouring water into the top of the length of bark made the children certain that very little water was being captured by the container at the bottom.

The first child redesigned the system, moving the length of bark to balance on top of two containers at the ends of the length (K-PS2-2 Motion and Stability: Forces and Interactions). She observed while pouring the water into the middle of the horizontal trough. Where do you think the water flowed in this new system design? 

There was time for one more redesign before going indoors for lunch. She added a third container on top of the trough in the center and poured water on top of the upside-down container. Where do you think the water flowed in this new system design?

Do you have any advice for creating bottle ecosystems with my seventh grade class? I would like them to do two-tier systems with terrestrial and aquatic organisms.

—S., Missouri

Students can learn a lot when they create these micro-habitats in plastic bottles with plants and invertebrates. The bottles can be stacked to form interdependent aquatic and terrestrial ecosystems. I’ve collected some resources in the NSTA Learning Center (https://goo.gl/o6ovVd) with more information.

Start the project by going over the different types of ecosystems and organisms. To get the organisms, you can sample a pond, flip over rocks and even visit a pet store before “build day.” I always kept a stock of these year-round in terraria and aquaria in my classroom. After spending a class researching the organisms available, students create a “shopping list” of the materials they need to add in their ecosystem. Have students bring in the two-liter bottles or ask colleagues for donations. Spend a class building the ecosystems and starting seeds of fast-sprouting plants like oats, radishes, greens, and alfalfa. Some students may want to use samples from an aquarium in their aquatic ecosystems. Have them explain why in their journal. A fleece wick between the lower, aquatic ecosystem to the upper, terrestrial ecosystem will facilitate water movement. In a few days the plants will sprout and students can add the invertebrates

Have the students write journal entries at least twice a week and stress accurate observations. If available, use oxygen and carbon-dioxide sensors as part of their data collection. Bio-geochemical cycles, pyramids and food chains/webs that depict their bottles can be incorporated into their journals.

I love bottle ecosystems and so did my students!

Hope this helps!

Photo by author

This week in education news, maker spaces help teach students to redesign their worlds; educator externships provide hands-on authenticity that better informs instruction and boosts teacher confidence; teachers wish they had more opportunities to further their careers while remaining in the classroom; across the country, most teachers don’t receive enough money to equip their classrooms and keep them running; President taps Kelvin Droegemeier as next White House science adviser; and Florida’s talent gap persists in the STEM occupations, despite the state’s booming economy.

‘I Can Do That!’: How Maker Spaces Teach Students to Redesign Their Worlds

As schools nationwide are expanding the use of maker spaces, researcher Edward Clapp spoke with Education Week about how teachers can get it right. Clapp is senior research manager on the Agency by Design initiative at Harvard University, which examines the promises of maker-centered learning. Read the article featured in Education Week.

K12 Educator Externships Provide Practical STEM Experiences

An externship program run by the Oklahoma State Department of Education expanded this summer, allowing K12 teachers to gain professional STEM experiences they can bring back to the classroom. During the pilot last year, teachers tested soil samples and worked in a concrete-making lab, among other activities, during a paid two-week externship at an Oklahoma City engineering firm. Read the article featured in District Administration.

It’s Time To Change Our Learning Model

As a 22-year-old first-year teacher, I was introduced to one of the biggest challenges within our schools. While setting up my classroom, my principal came by to deliver a set of fifth-grade textbooks and an analysis of the starting points for each of the 28 students in my class. While all of my students were in fifth grade, they were individuals starting at varying places academically. I worked hard, cared a lot, and spent lots of late nights developing lessons. I tried to learn how to keep the classroom orderly and motivate my students to learn. And I tried to learn all I could from my colleagues who had far more experience, knowledge, and skill than I had. Read the article featured in eSchool News.

What’s School Without Grade Levels?

On windswept fields outside Fargo, North Dakota, a bold experiment in education has begun. In a lone building flanked by farmland, the Northern Cass School District is heading into year two of a three-year journey to abolish grade levels. By the fall of 2020, all Northern Cass students will plot their own academic courses to high school graduation, while sticking with same-age peers for things like gym class and field trips. Read the article featured in The Hechinger Report.

Teachers Weigh In On Pay, Safety, School Choice, And Evaluations in New Survey

In a year marked by teacher activism and demonstrations, educators are urging policymakers to listen to them. Now, a new survey details teachers’ opinions on more than a dozen education issues. Read the article featured in Education Week.

Cash-strapped Teachers Turn To Facebook, Online Sites To Equip Their Classrooms

When teacher Shemena Shivers walked into her Melrose High School science lab for the first time, she couldn’t contain her excitement at the closet full of equipment and supplies. But after a closer look revealed long-expired solutions and outdated texts, she realized that she would need to spend hundreds of dollars out of pocket just to provide her students a basic science education. So, she did what many of her fellow teachers have done: She turned to Facebook for help. She created a video of her classroom, issued a heartfelt online plea and posted a link to her supplies campaign on MTR Give, a fundraising site run by the teacher-training program she had attended. Read the article featured in Chalkbeat.

Trump Taps Meteorologist As White House Science Advisor

U.S. President Donald Trump will nominate meteorologist Kelvin Droegemeier as his government’s top scientist. If confirmed by the Senate, Droegemeier would lead the White House Office of Science and Technology Policy (OSTP). Trump, who took office 19 months ago, has gone longer without a top science adviser than any first-term president since at least 1976. Read the article featured in Scientific American.

Building A Talent Pipeline To Meet STEM Demands

Florida’s economy is booming, yet, as other states also are experiencing, the talent gap persists in many of our targeted industries, particularly in science, technology, engineering and math (STEM) occupations. Read the article featured in the News-Press.

Stay tuned for next week’s top education news stories.

The Communication, Legislative & Public Affairs (CLPA) team strives to keep NSTA members, teachers, science education leaders, and the general public informed about NSTA programs, products, and services and key science education issues and legislation. In the association’s role as the national voice for science education, its CLPA team actively promotes NSTA’s positions on science education issues and communicates key NSTA messages to essential audiences.

The mission of NSTA is to promote excellence and innovation in science teaching and learning for all.

Follow NSTA

President Trump Signs Career and Technical Education Bill

Congress finally passed, and President Trump signed into law, a reauthorization of the Carl D. Perkins Career and Technical Education Act on Tuesday, July 31.

The bipartisan bill, which has not been reauthorized since 2006, will provide $1 billion to states for secondary and post-secondary skill training.  It has the support of governors, the U.S. Chamber of Commerce and most education groups and was heavily championed by the Administration, notably the president’s senior adviser Ivanka Trump, who has made workforce issues a priority.  

During the signing of the Strengthening Career and Technical Education for the 21st Century Act President Trump said, “we will continue to prepare students for today’s constantly shifting job market, and we will help employers find the workers they need to compete.”

The new law will apply to the 2019-2020 academic year. It allows states to set their own career and technical education goals and it eliminates an existing negotiation process between states and the Education secretary, who still approves the state plans.

The goals would be built around specific “core indicators” outlined in the bill, such as high school graduation rates and the percentage of CTE students who enroll in post-secondary programs. Schools would also be required to make “meaningful progress toward improving the performance of all career and technical education students.”

Although no specific provisions are related to STEM education, the bill does call out STEM subjects, including computer science, and better connects career and technical education (CTE) to local workforce needs.  

Trump Picks Meteorologist Kelvin Droegemeier to Lead White House Science Office

President Trump has selected well-known meteorologist Kelvin Droegemeier to head up the White House Office of Science and Technology Policy, a decision that was widely praised by members of the scientific community. According to the American Institute of Physics, Droegemeier—who has spent his career at the University of Oklahoma (OU) and is the university’s vice president for research—“has contributed extensively to science policy at the national, state, and professional levels.” Read more about the selection here.

White House Requests Federal Agencies to Prioritize STEM Education in FY2020 Budgets

In a memo on the Administration’s Research and Development Budget Priorities, the White House requested that federal agencies prioritize STEM education and workforce development as they develop their fiscal 2020 budgets.

“Federal R&D dollars focused primarily on basic and early-stage applied research, paired with targeted deregulation, and investment in science, technology, engineering, and mathematics (STEM) education and workforce development, will strengthen the Nation’s innovation base and position the United States for unparalleled job growth, continued prosperity, and national security,” says the memo signed by Mick Mulvaney, director of the Office of Management and Budget (OMB) and Michael Kratsios, deputy assistant in the Office of Science and Technology Policy.

“Agencies should prioritize initiatives that reskill Americans for the jobs of today and the future,” the memo also says. “Education in science, technology, engineering, and mathematics (STEM), including computer science, will be foundational to preparing America’s future workforce, and should be integrated into instruction through application to real world challenges. Agencies should work to ensure the STEM workforce includes all Americans, including those from urban and rural areas as well as underrepresented groups.”

Administration Puts Spotlight on Workforce Training

Also last week President Trump signed an executive order “to prioritize and expand workforce development” by creating a senior-level National Council for the American Worker panel that will “develop a national strategy for training and retraining workers for high-demand industries.”

An advisory board comprising leaders from the private sector, educational institutions, philanthropic organizations and state governments will also work with the administration “to implement results-driven job-training programs in classrooms and workplaces across the country.”

The report notes that “workers and educational institutions are separated from employers by an information gap that makes it difficult to prepare the workforce with the skills employers seek. The information gap is exacerbated by a dearth of data and weak comparability of skill requirements. Coordination among these parties will be crucial for addressing America’s reskilling challenge.”

White House Presidential Advisor Ivanka Trump outlined the report in a Wall Street Journal op-ed. Read the full report here.

Trump Administration to Overhaul Federal Rules on Accreditation

The U.S. Department of Education has published a notice in the Federal Register that it intends to convene a negotiated rulemaking committee in January to develop proposed regulations that would revise current federal rules set in place during the Obama Administration related to the Secretary’s recognition of accrediting agencies and non-traditional education providers .

The proposed topics for negotiation would include:

• Requirements for accrediting agencies in their oversight of member institutions;
• Requirements for accrediting agencies to honor institutional mission;
• Criteria used by the Secretary to recognize accrediting agencies, emphasizing criteria that focus on educational quality;
• Developing a single definition for purposes of measuring and reporting job placement rates; and
• Simplifying the Department’s process for recognition and review of accrediting agencies.

Three public hearings will be scheduled to discuss the rulemaking agenda: September 6, 2018, at the U.S. Department of Education in Washington, DC; September 11, 2018 in New Orleans; and September 13, 2018, at Gateway Technical College in Sturtevant, WI. Read the Federal Register notice here.

ICYMI – NSTA Executive Director to Co-Chair National STEM Education Advisory Panel

NSTA Executive Director Dr. David Evans has been appointed by the National Science Foundation to serve as the vice chair for the National STEM Education Advisory. The panel was created to encourage U.S. scientific and technological innovations in education, and to advise a group of federal organizations called the Committee on Science, Technology, Engineering and Mathematics Education (CoSTEM) on matters related to STEM education. They will also help to update CoSTEM’s 2013-2018 Federal STEM Education 5-Year Strategic Plan.

In addition to David, two classroom teachers and NSTA/NCTM STEM Teacher Ambassadors—K. Renae Pullen and Bruce Wellman— have also been named to the panel and NSTA Past President Arthur Eisenkraft has also agreed to serve.  Read more here and here.

Stay tuned, and watch for more updates in future issues of NSTA Express.

Jodi Peterson is the Assistant Executive Director of Communication, Legislative & Public Affairs for the National Science Teachers Association (NSTA) and Chair of the STEM Education Coalition. Reach her via e-mail at jpeterson@nsta.org or via Twitter at @stemedadvocate.

The mission of NSTA is to promote excellence and innovation in science teaching and learning for all.

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Oxygen is one of those very cool elements that can both save a life and kill whether in absence or abundance. Oxygen is necessary for life as we know it, but yet it oxidizes one of the most common elements in the universe. Oxygen, to most students, is both a red ball on a model and a common test question answer. But to fully appreciate oxygen, students need to measure it. And as an odorless, tasteless, colorless gas, oxygen is filled with surprises, and also science essentials.

The history of the discovery of oxygen has plenty of twists and turns stretching from the second century BCE to the present. The path to discovery and understanding of oxygen is truly a who’s-who of science and philosophy. Whether Philo of Byzantium or Leonardo da Vinci or Robert Boyle or Antoine Lavoisier, or even Charles Darwin, the road to oxygen is paved with greatness. And don’t forget that Robert Goddard, the father of modern rocketry was the first to use liquid rocket fuels and one of those was liquid oxygen.

The Extinction of Words

A notable causality of the progression towards the understanding of oxygen was the word dephlogisticated. Back about the time America was just starting its grand experiment, around 1776, the word dephlogisticated was used to describe the portion of air now known as oxygen. Unfortunately for the word dephlogisticated, however, as the pace of science increased so the need for the word dephlogisticated decreased. Dephlogisticated, by the way, means dephlogisticated or without phlogiston. Ok, so much help with that. So a better explanation might be that phlogiston is a chemical involved with combustion. So dephlogisticated is the lack that chemical.

Regardless, the use of the word dropped of off a cliff after 1800. Presumably the speed of “viral” back in the 19th century would be on the speed of decades. So Dephlogisticated died a quick death over a 25 year period. By 1825, the word was at risk. By 1875, the word was on the endangered species list. And at the beginning fo the 21st century, the word was only found in museums and zoos and historical footnotes like this blog.

Plug n’ Play? What’s That?

The measurement of oxygen is a staple in science education, and O2 sensing has never been easier. With Vernier’s new Go Direct Oxygen Gas Sensor, the ability for students to measure relative oxygen concentration has never been easier or faster. Using Vernier’s Graphical Analysis 4 App, with self-identifying sensors, plug-n-play truly is plug-n-play even though we have recently transcended plugs.

An interesting misconception surrounding the measurement of oxygen in the air is that while we refer to a lower amount of available O2 in the air as elevation increases, the concentration of oxygen as a percentage of overall air remains the same. However, since there is less overall air density, there is are fewer overall oxygen molecules for the breathing even though the percentage of (20.9ish%) oxygen is the same everywhere, up or down. In other words, the percentage of oxygen in the air is always about 20.9%,  even on the summit of Mt. Everest so instead we use an “effective oxygen percentage” that is used to make an understandable approximation that provides usable information when dealing with living organisms. For instance, at sea level, the O2 effective O2 is 20.9%. At 5000 feet or 1500 meters, the effective O2 concentration is 17.3%. Ten thousand feet or 3000 meters is 14.4%, and 20,000 feet (6000m) is 9.7% effective oxygen. The top of Mt. Everest at over 29000 feet (8800m) is 6.9% effective oxygen or exactly one-third of the effective oxygen at sea level.

Mt. Everest. Photo from Wikipedia.

I’ve thought about how to explain this to students and I think a reasonable model would be a set of marbles of different colors. For every 100 marbles, there will be 21 red ones (oxygen), 78 blue ones (nitrogen), and one mostly green one (mostly argon, a fraction of CO2, and a pile of other odds and ends in concentrations no more than a thousandth of a percent). So at any given altitude, the proportion of marbles of a certain color remains the same. Its just that the marbles are spread throughout a larger volume due to the lower atmospheric pressure. As atmospheric pressure drops, so too does the ability of the lungs to exchange the gas.

The Vernier Go Direct O2 wireless sensor in airline back seat pocket.

The Vernier Go Direct O2 Gas Sensor is one of two O2 sensors in the Vernier lineup. As a wireless probe the Vernier Go Direct O2 Gas Sensor provides all the necessary capabilities of an O2 sensor with none of the pesky cables that limit use, knock over experiments, and require an additional interface.

Of course, if you need to cable the Go Direct, you can using a basic micro-USB cable. So simple is the Vernier Go Direct O2 Gas Sensor that I handed it to a student while we were on a trip to a NASA facility for a week of STEM inspiration (as only NASA can). After take off, and upon reaching the 10,000 foot level where approved electronics can be used, she fired up the sensor and was shocked to see the O2 level drop from measured take-off level to a deliberate sub-16% effective O2 concentration, something in the effective range of about 7500 feet (2200m). That particular O2 concentration is at the high end of what is considered the medium altitude category. Any higher and it would cause discomfort for the average sea-level dweller.

And upon landing, at 10,000 feet the cabin O2 level rose as landing apporached.

Of course the usefulness of the Vernier Go Direct O2 Gas Sensor is not limited to those out-of-classroom experiences risking life-and-limb or other hyphenated landscapes. Classic science experimentations are the Vernier Go Direct O2 Gas Sensor’s forte’. Vernier suggest some popular experiments including testing for catalase under various conditions, measuring oxygen consumption at rest and after exercise, measuring the change in gas produced during photosynthesis, and comparing the rates of cell respiration in germinating and non-germinating peas.

Science by Candlelight

A kitchen-table experiment I ran with the Vernier Go Direct O2 Gas Sensor involved a cookie jar and a candle. Watching a candle burn out in a closed environment is a staple of science education, and of all the variants of that experiment, none have used the Vernier Go Direct O2 Gas Sensor until now. Watching the O2 level drop right next to the flame was insightful. It immediately raised the question of at what relative elevation did the candle go out? Turns out that’s equivalent to about 10,000 feet. So the next question is can you burn a candle at 10,000 feet? And from there the questions just piled up. Ahh, such is science.

https://youtu.be/OaXwkvx7j-I

One observation that a high school junior noticed when running the experiment a few times is that at the lower oxygen concentrations, the BIC lighter used to ignite the candle would not light until there was enough oxygen back into the container. In other words, the candle could not be relit until the O2 level inside the container rose to at least 17%.

To enhance the capabilities of the Vernier Go Direct O2 Gas Sensor, I made a stand to keep the Vernier Go Direct O2 Gas Sensor upright. With nothing more then the cut-off top and bottom of a water bottle, a conical stand for the sensor materialized. Just lop off the top of a plastic water bottle. Open the top just big enough for the sensor to fit through, and cut the bottom a few centimeters below the business end of the sensor. Then cut a few triangular openings into the base and you are good to go. Another option I drew upon was to repurpose a flashlight holder that allows the Vernier Go Direct O2 Gas Sensor to be used in various situations while supported, padded, hanging, and upright.

The easiest upright storage method, however, is to use the included 250 mL gas sampling bottle (Nalgene bottle with lid). 

Stand Upright

The nature of the Vernier Go Direct O2 Gas Sensor requires that it be stored upright to maintain its effectiveness. According to Vernier, “The cell contains a lead anode and a gold cathode immersed in an electrolyte. Oxygen molecules entering the cell are electrochemically reduced at the gold cathode. This electrochemical reaction generates a current that is proportional to the oxygen concentration between the electrodes. The sensor output is a conditioned voltage proportional to the reaction current.” Further, Vernier’s website states, “As your O₂ Gas Sensor ages, the readings will decrease. This is normal, as the chemicals in the electrochemical cell are depleted. It does not mean the sensor is no longer functional; rather, it simply requires that you perform a calibration and store it as described previously.”

I got my first Vernier O2 gas sensor last century. Its much like the cabled version still available from Vernier, but with harder edges, more primitive billboarding, and an aggressive calibration button. The latest cabled version has a smooth domed top, pleasant green O-ring dampeners, and a large “OXYGEN” statement declared around the core of the unit.

Regardless of the unit, the nature of an O2 sensor has some limitations with regard to storage orientation. Those suggestions are more like warnings if you want to stretch the maximum life out of your O2 sensor.

Think Outside the Analog

What I find interesting, as an aging science teacher, is that we are finally able to push the boundary of what we want to do beyond just what we can do. The Vernier Go Direct O2 Gas Sensor pushes the boundary of experimental measurement forcing a teaching evolution beyond the analog. We can now fulfill the dream as science teachers to where our students leave us behind as they accelerate past us. By standing on our shoulders and jumping towards the sky they begin to fly!