At room temperature, elemental (metallic) mercury can evaporate to become an invisible, odorless toxic vapor. The warmer the air, the more quickly mercury vaporizes. Exposure to even a small amount can affect your health. Symptoms can surface within hours of exposure. According to the Centers for Disease Control and Prevention (CDC), exposure to mercury can result in short-term symptoms (e.g., coughing, vomiting) and long-term symptoms (e.g., loss of appetite, memory loss).

The problem with mercury is that it keeps on recycling itself. It vaporizes, is absorbed by materials in the environment (e.g., carpet, cloth, wood, window fixings), and again vaporizes into the air. This means that mercury drops can continue to turn into vapors that are breathed in by students and teachers years after a spill. It keeps recycling unless there is an intervention.

To determine if there is mercury in the lab, either secure a mercury detection kit or have a commercial lab test the science lab for mercury. If the results come back positive, the school district will need to hire a mercury spill clean-up contractor. If there is a small spill from, say, a broken mercury thermometer, see “How to handle a mercury spill” below.

Where can mercury be found in schools?

For decades, science teachers have used mercury in demonstrations and lab experiments involving oxygen production, exceptionally strong cohesive forces, and more. Before the health concerns about elemental mercury were evident, it could be found in a number of sites at schools, especially in science labs (e.g., glass thermometers, pressure gauges, batteries). Beyond the science lab, mercury can be found in fluorescent lamps and light bulbs, thermostats, switches, latex paint (produced prior to 1992), old microwave ovens, high-intensity discharge lamps, and silent, mercury-tiltwall switches.

All mercury instrumentation and mercury compounds need to be removed from labs appropriately. There are mercury thermometer exchange programs at the local and state levels, commercial hazardous waste vendors, and science laboratory equipment/supply houses.

Alternatives to mercury

Alcohol or electronic thermometers should replace all mercury-filled thermometers. There are also accurate alternatives to mercury barometers, vacuum gauges, manometers, and sphygmomanometers (blood pressure gauges) that rely on electronic or digital gauges and aneroid gauges. Other less hazardous chemicals such as a copper catalyst or zinc formalin can be in place of mercury for science demonstrations and experiments.

How to handle a mercury spill

Should there be a mercury spill, its size will dictate the response. Prepare for a spill by determining the mercury cleanup protocol from your school’s administration or board of education. In addition, general mercury spill guidelines are available from numerous sources, including most state departments of environmental protection and the Environmental Protection Agency. The EPA’s guidelines provide information on cleaning up mercury spills, including what never to do after a spill, preparation for cleaning up a broken mercury thermometer, materials for cleaning up the spill, and specific instructions for cleaning up a spill.

Submit questions regarding safety in K–12 to Ken Roy at safesci@sbcglobal.net or leave him a comment below. Follow Ken Roy on Twitter: @drroysafersci.

NSTA resources and safety issue papers
Join NSTA
Follow NSTA

What are some of the best ways to start and facilitate a class discussion about science topics?

– B., Arkansas

I have used many different ways to get science discussions going. I think the key is to either “wow” them or provide them with some structure to get the ball rolling.

If you have a really good demonstration or discrepant event (such as a skewer through a balloon or an ammonia fountain) the students will perk up and take notice. Have them work in groups to figure out how it worked and then have a full class discussion of the answers.

Start a new topic with a What I Know–Want to find out–Learned (KWL) chart. Have students fill in the K column and at least two items in the W column, then share their work with a partner. They can challenge their partners’ knowledge or agree with them. They may even be able to answer their partners’ questions. Anything they learn goes in the L column. You can have students share their questions with the whole class. This launches the next phase of learning where they get their answers.

Graphic organizers can lead discussions—there is a variety online. Students start on their own and then share. I found a few online and have them in a collection in the NSTA Learning Center. (https://goo.gl/yZNHNB)

Hope this helps!

SeedDiscussion

Photo Credit: U.S. Department of Agriculture

For almost 2000 years, Aristotle’s ideas about weather were the industry standard. Although our hindsight confirmed that many of the theories Aristotle put forth in his work Meteorologica were in error, the depth and breath of his observations and inferences were truly impressive especially given his lack of instrumentation and the non-non-existant units that an instrument could produce.

While inferences are conclusions about the cause of an observation, when it comes to weather, we want to know the future, not just the present. Predicting weather, although wrought with more than it’s fair share of failures and punchlines, it is a staple of our daily routine.

Time and temperature are two foundations of our universe, with time being a measurement of change and temperature being a relative quantity of atomic motion. Pretty much everything else is wrapped up in those two concepts. But what about the details? The small stuff. The other stuff.

A foundational concept of geology, uniformitarianism, is to discern the past by observing the present. Water erodes land. Wind blows sand around. Ice cracks rock. And gravity tries to flatten everything out. Weather, on the other hand, is predicted by inferring what we think caused what we are experiencing now. This double-inference is especially tricky. Ideally though, with enough data points, we can know the future. Well, at least the short-term weather.

Three hundred years before Aristotle, the Babylonians tried to predict short term weather changes based on the look of cloud and other visible changes. And shortly after Aristotle penned his four tomes on weather theory, the Chinese constructed a 24-part annual calendar based on different weather types.

What was missing, and what kept archaic ideas alive for millennia was primarily the absence of instrumentation and quantitive measurements. Qualitative observations lacked both precision and comparative metrics, and without those it was difficult to generalize descriptions across geography and time.

Breakthroughs were made with the creation of instruments used to measure humidity, temperature, and barometric pressure allowing both discrete measurements and inferred measurements by combining types of data. And as electronic communications increased, so did the ability to compile distant observations and measurements, and to make forecasts with the ability to check one’s work.

By the 1860s the combination of many data points across a large area through telegraph communication made weather forecasting a real thing. The accuracy and scope of predicting the weather made another leap when the instruments were attached to weather balloons and rose through the atmosphere adding a third dimension of accuracy.

The next big break in wether prediction was numerical analysis of the data. What was needed was a formula where the variables could be entered resulting in a solution that accurately predicted the weather at a point in the future. And as the equation was refined, accuracy improved and the reach into the future was greater. Oddly, from Aristotle’s methods of 2300 years ago until 19 years before we went to the moon, using all the math and instrumentation possible, we measured success by predicting the weather a full 24 hours into the future.

Today, we combine all the best of our instruments and equations along with space-based satellites allowing us to predict weather with much more accuracy and much farther into the future. But even that has not dampened weather’s role in jokes and punchlines.

Weather stations of various quality have been part of the science classroom for decades. Beginning with the simple indoor/outdoor thermometer, quantitative weather observations have been a popular part of the daily classroom routine whether morning homeroom or science curriculum from kindergarten to graduate school.

What has changed over recent time is the shape and capabilities of the weather station. From boxes within larger boxes, to individual instruments bolted and wired together, all with their own limitations. One of the biggest challenges is the data collection, well actually the data extraction and visualization. Half of science is data collection. The other half is data interpretation. The former without the latter is useless. The latter without the former is, well, fake news.

The Pasco Wireless Weather Sensor

Pasco has created a unique and intensely feature-filled weather station that contains 17 different measurements or extrapolations. As if that weren’t enough, the quarter-pound of sensors in the Pasco powerhouse can share it’s finding with a computing device through a USB cable, through Bluetooth, or just hang on to them inside its built-in memory until a later time. That means the weather station can transfer it’s weather data, current or over time or both, from a few cabled meters away, like magic through the air via Bluetooth up to 10 meters away, or 12,756 km away using independent datalogging only to be picked up at a later date and downloaded. By the way 12,756 km is the farthest any two points can be from each other on planet earth.

And you can keep track of you place on the earth because the Pasco Wireless Weather Sensor has built-in GPS.

Pasco.com lists the sensors and specs as:

One essential accessory for the Pasco Wireless Weather Sensor is the Weather Vane Accessory. The three pieces in this kit include a tripod mount allowing free 360 degree spin, a screw-in boom, and a tail fin. By adding 20cm of distance between the Pasco Wireless Weather Sensor and 48 square centimeters of wind-grabbing vertical wing, the Weather Vane will keep the Pasco Wireless Weather Sensor’s turbine anemometer perpendicular to the wind. The kit also comes with a stout table-top tripod with excellent leg-spread and a ball head for quick adjustment and solid lock-up.

The tripod kit also makes an excellent handle that removes any directional bias from simply holding the Pasco Wireless Weather Sensor in your hand and pointing it towards where you think the wind is coming from. Additionally, the stiffness of the metal tripod legs allow it to be form fit to a slanted surface without raising the center of gravity much.

The built-in USB rechargeable lithium polymer battery powers all the sensors, the GPS, and of course the Bluetooth radio that effortlessly transmits the data to any compatible device with Pasco SPARKvue software including those running iOS, Android, ChromeOS, Mac and Windows.

The Pasco Wireless Weather Sensor can directly measure wind speed, wind direction, barometric pressure, humidity, ambient temperature, light level, UV index, and magnetic heading. With that information, the software can calculate dew point, wind chill digital-compass wind direction, absolute humidity, and heat stress index. The on-board GPS receiver can identify latitude, longitude, altitude, speed, wind direction (with declination adjustment) and number of satellites the Pasco Wireless Weather Sensor is listening to.

While most of the measurements are self-explanatory, a couple of them can be confusing. Dew point, for instance, is the temperature to which air must be cooled to become saturated with water so at any lower temperature than the dew point, water condenses out of the air making dew. If the dew point is below freezing, then its called the frost point since frost forms rather than liquid dew.

The relationship between dew point and humidity is that humidity is a direct measurement of the amount of water vapor present in  the air. The higher the humidity, the closer the measured humidity and the calculated dew point. At 100% humidity, the dew point is equal to the ambient temperature.

Wind chill, windchill, wind chill factor, or wind chill temperature; it doesn’t matter what you call it, it is a calculated number below the ambient temperature that considers convective heat loss on a surface similar to human skin. The idea is that ambient temperature alone does not provide general information about how cold it feels, and how the body will react. Convective heat loss can make a temperature behave and feel much colder than if there was little convection. And since convection can easily be countered with modern fabrics and outdoor clothing, and being inside a car, the application of the wind chill factor are mostly limited to those situations where unprotected (direct skin) exposure to the wind can happen.

The calculation of windchill involves wind speed, air temperature and some constants that are generally agreed upon to represent human skin. Over time, the constants have changed, and even today they vary across continents. However, in 2001, the Joint Action Group for Temperature Indices (JAG/TI) updated the wind chill temperature index adding or specifying the following:

• Use calculated wind speed at an average height of five feet (typical height of an adult human face) based on readings from the national standard height of 33 feet (typical height of an anemometer);
• Be based on a human face model;
• Incorporate modern heat transfer theory (heat loss from the body to its surroundings, during cold and breezy/windy days);
• Lower the calm wind threshold to 3 mph;
• Use a consistent standard for skin tissue resistance; and
• Assume no impact from the sun (i.e. clear night sky).
  

  ---

The calculated Heat Stress Index is basically the relation of the amount of evaporation or perspiration required to cool a body compared to the maximum ability of the average person to perspire.  Somewhat similar but opposite of the wind chill factor, the heat stress index uses ambient temperature and humidity along with some assumptions (constants in the equation) to generate a temperature number above the ambient temperature. The Heat Stress Index can kick in at 80 degrees F, and climbs rapidly from there. The concept here is that it takes energy to vaporize (evaporate) water. The human body excretes water through sweat glands and as that water evaporates, energy is lost thus cooling the body. But in order for the water to evaporate, there must be “room” in the air for it. As humidity climbs, there is less and less room until 100% humidity is reached at which point there is no room so essentially the body’s cooling mechanism is completely ineffective. Some examples include at 96 degrees F, the heat index is 108 at 50% humidity, and 132 at 75% humidity. And 90 degrees F, the heat index is 108 at 75% humidity and 132 at 100% humidity. However, 100% humidity at 80 degrees F only yields a heat index of 87. I am using Fahrenheit since most US weather measurements and Heat Indexes are reported in such units whatever we call them now like British, English, SAE, non-metric, fractional, U.S. units, Imperial, or the formal sounding USCS for United States customary system.

The way the instrument works is almost as much fun as using it. For instance, temperature is measured by a thermistor which, like it sounds, is a electrical resistor that changes its resistance as temperature changes. Temp goes up, resistance goes up. Temp goes down, resistance goes down. So when the resistance is calibrated to the temperature, the flow rate of electricity now tells the temperature.

Another chip, the humidity sensor also uses resistance. In this case the electricity flows through electrodes embedded in a water-absorbing resistive polymer material exposed to the air. As moisture (humidity) is absorbed into the polymer, the resistance changes and so does the reported percentage of water vapor in the air known as humidity. Of course you can complicate matters by splitting the hairs of absolute humidity, relative humidity, and specific humidity.

Finally is the turbine anemometer, by far the coolest moving part on the Pasco Wireless Weather Sensor. Like a tiny six-bladed ship’s propeller, the twirling blade spins almost effortlessly inside its tube generating an electric current corresponding to its speed.  And as the only major moving part in the Pasco Wireless Weather Sensor, it is replaceable.

The Pasco Wireless Weather Sensor is controlled by the software on a computing device. Pairing the sensor with Bluetooth allows control over what instruments are monitored, and even to turn some of them on or off. For example, you may want a data collection run over several days, but in the same location. In that case, the power-hungry GPS receiver and power thirsty digital compass can be turned off to substantially increasing the runtime.

The SPARKvue software platform is available from Pasco in any of 28 different languages including Kazakh, Thai and Turkish as well as several flavors of Spanish, French, Chinese, and Portuguese. In SPARKvue, you can build a visual interface that shows up to six of the sensors in real-time. You also have the choice of individual graphs, gages, numbers and other measurement presentations.

Mark Twain once said that, “Climate is what we expect, weather is what we get.” I once said, “If you don’t like the weather here in Montana, wait an hour. It will get worse.” No matter who you quote, teaching about the relationship between current weather, future weather, and the measurements we use to bridge the time gap is not only important, but with 33 hits for the term weather in the NGSS Standards (only 26 for the term Force, but 77 for the term Chemical), I’d label weather as an important science topic in need of attention at all grade levels.

Even in the future when each school district has its own weather satellite, there will still be a need for local measurements, and the simplification of large scale phenomena. Tools such as the Pasco Wireless Weather Sensor will be an invaluable component in making the abstract concrete, the enormous manageable, and the experience quantifiable. Just imagine if Aristotle had his own Pasco Wireless Weather Sensor. We might be two thousand years more advanced than we are now!

Janet Sweat’s middle school students in Lake City, Florida, disassembled broken toys
to create cars, some that would run with remote controls and others without them. Photo courtesy Janet Sweat.

A breakerspace—a makerspace workstation where students can disassemble toys, electronics, and appliances—engages students “in the ‘how does this work,’ ‘what makes things work,’ ‘I wonder,’ and tinkering phases of investigating the world around them. In the age of touch screens, cell phones, headphones, etc., it is important to stress engaging with others and the world around them and to foster [students’] curiosity,” says Cynthia Crockett, science education specialist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. “This is not a new phenomenon—the ‘take-apart table’ [dates back to] the 90’s—but…[it] has seen a resurgence [recently] with the advent of makerspaces.”

Crockett emphasizes that “no smashing or wanton destruction [is] permitted; that defeats the very purpose.” Instead, teachers should encourage students to “explore and move toward understanding the workings,” which happens when students study objects “to figure out how to ‘get inside,’ see how it is put together…‘ undo’ it, then…[re-examine it].” Students can further their learning by reassembling the item, she adds.

When Janet Sweat of Lake City, Florida, taught middle school, her students “would take apart broken toys to create cars that run. We would repurpose motors and create circuits…A broken PlayStation became a car with a pop-up top and headlights,” she recalls. “The students were extremely creative.”

Sweat had students sketch their creations beforehand. “The art piece was necessary [to show] what will the thing look like? What is the energy source? How will the circuit be designed?”

Afterward, the students “remembered those circuits and did well on tests,” she asserts.

Lucas Carr, technology teacher at Sullivan North High School in Kingsport, Tennessee, says his breakerspace “is a large part of my classroom…I have had students run through labs [in which] we took older/inoperable computers apart; students have brought in old electronic toys to repurpose parts; and we also compete in robotics competitions, which have involved many disassemblies of completed robots. In all, I believe these activities offer increased student motivation, and an opportunity for educators to present the knowledge and skills that students need to work with 21st-century concepts and equipment.”

Carr has a closet designated for storage of items to be dismantled. “One of the biggest challenges is having enough space so you can keep a good supply and give students a range [of items] to choose from,” he reports. 

While Carr’s students are most focused on electronics, he suggests teachers who want to establish a breakerspace “start with what you’re most familiar with.” Some teachers and students might be more comfortable working with “dolls and stuffed toys, or old lawnmowers,” he notes.

“Our Makers’ Lab has always had a take-apart space, as well as our Tinkering carts and spaces…Our largest item was a washing machine disassembled by kindergartners,” says Matt Pearson, director of the Makers’ Lab at Marin Country Day School in Corte Madera, California. Before students work with “CRT [cathode ray tube] TVs and microwaves, which are high-voltage,” Pearson says he removes “the dangerous pieces” from microwaves and ensures the capacitors in electronics are discharged. 

“I’m most interested in electromechanical items like pulleys, gears, motors, and switches because students learn a lot more” from them, he contends. “My most sought-after take-apart is the VCR [videocassette recorder]” because of “the many simple machines and electromechanical parts it contains. Students gaining an understanding of simple machines directly connects to the NGSS [Next Generation Science Standards] engineering standards in grades 3–5. An understanding of transferring or transforming energy is most easily taught with simple machines doing a task. VCRs have many.”

To initiate a project, students “have to formulate a pitch, why they want to do it, and argue it, like in the real world,” says Pearson. “They have to do research…I give them a budget for carrying out the project,” he relates.

“You have to foreshadow the takeapart, so I do it myself first,” Pearson advises. Students have to demonstrate the safe use of tools before using them.

Tinkering, he says, “serves as the creative and innovative connection between Making and STEAM [science, technology, engineering, arts, and math]. A STEAM education environment includes creative, stimulating, and inspiring classrooms where creativity is used to problem-solve interesting and culturally relevant challenges. I suggest that Making is the gateway to such a classroom, with Tinkering serving as the means to acquire new knowledge and skills and explore how to recombine the traditional in innovative ways.”

Anthony Perry, invention education coordinator for the Lemelson-MIT Program—which encourages students to invent and develop hands-on STEM skills—has facilitated summer camps in which elementary and middle school students learned engineering design by disassembling electronics. Students entering the camps typically “had zero experience working in a group. [They learned] you can’t do it alone; you depend on your teammates,” he asserts.

The camps also helped students develop persistence, he says. “Things aren’t going to work right away. You have to change course, ask a peer, or try something else.”

Perry had students keep engineering notebooks. “For each step, they would sketch it out and make observations,” he recalls. The notebooks also “made it clear that smashing something is not the way to learn about [electronic circuits and systems].”

Suggestions for Safety

“Like with any type of demolition work, safety preparation is critical,” asserts Ken Roy, NSTA’s chief science safety compliance consultant. He cites “the need to be aware of personal protective equipment requirements and appropriate use [e.g. eye (safety glasses or goggles) and hand protection (work gloves)]; the need to work [safely] with hand tools; and the need to assess hazards and determine risks of materials/equipment to be worked with.”

Above all, students must be trained “on all of these safety issues noted and [successfully assessed before doing]… breakerspace activities. Teachers [must] make sure [to have] continuous and direct adult supervision of students…under ‘duty or standard of care’ legal requirements…to ensure that behavioral expectations are being followed and to be prepared for the unexpected safety issues.”

For a complete list of safety procedures for breakerspaces, see Roy’s safety blog.

This article originally appeared in the April 2018 issue of NSTA Reports, the member newspaper of the National Science Teachers Association. Each month, NSTA members receive NSTA Reports, featuring news on science education, the association, and more. Not a member? Learn how NSTA can help you become the best science teacher you can be.

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

Follow NSTA