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Student behaviour in the MOOCosphere

I’ve written a few times recently about the rise of massive open online courses, or “MOOCs” for short. If this trend in education has so far passed you by, MOOCs are online courses generally offered free of charge by some of the leading universities in the world. For example, Massachusetts Institute of Technology offers courses in classical mechanics and electricity & magnetism, and the University of Edinburgh has recently launched a course about the discovery of the Higgs boson.

MOOCs tend to combine video lectures with assignments such as problem sets and extended projects. In many ways, the course formats mirror or complement traditional classroom-based education, incorporating features such as forums where students can discuss the course content amongst themselves. Some of the science courses even include online “practicals” by way of virtual laboratories. But despite the proliferation of MOOCs in the past few years, very little research has been carried out on the way that students are actually engaging with the courses.

Now, a group of researchers in the US has done the first relatively detailed study of student behaviour in the MOOCosphere. The study is described in a paper published on the arXiv preprint server with lead author Ashton Anderson, a computer scientist at Stanford University. Anderson and his team examined the behaviour of the student population in courses offered by Stanford through Coursera, one of the major MOOC providers. The courses were on the topics of machine learning and probabilistic graphical models. After reading the study, it seems to me that the “take away” message is that MOOC students have many different motivations for taking these courses and as a result they behave in an assortment of ways, distinct from classrooms in the real world.

“Rather than think of MOOCs as online analogues of traditional offline university classes, we found that online classes come with their own set of diverse student behaviours,” write the authors.

Five types of student

The study places MOOC students into five distinct categories. There are the “all-rounders” who are essentially the class keen beans who watch most of the video lectures and complete most of the assignments. There are the “viewers” who primarily watch the video lectures but don’t bother handing in many assignments, many of whom may be tuning in for general interest. Conversely, there are the “solvers” who skip most of the lectures but hand in assignments, perhaps because they already know a lot of the course content from previous study. There are the “collecters” who download lots of lectures but don’t hand in many assignments, and finally the “bystanders” who register for the MOOC but don’t bother to show up once the course has started.

The thing that struck me when I saw these categories is that this behaviour does seem to mirror behaviour in traditional classrooms, despite what the authors conclude about the distinct MOOC student behaviour. Anyone who attended a bricks-and-mortar university will surely recognize all of the above personality traits among their peer group. I’m sure you can all recall a few “viewers” who turned up to most lectures but couldn’t be bothered with the homework. Likewise, I’m sure you all remember those annoying “solvers” who skipped most of the lectures but still managed to get top marks on the assignments.

Anything for a shiny badge

One other interesting feature of the study is an analysis of the discussion forums that are available to students taking the courses. Anderson and his team found that students engaged more with these forums when they were offered electronic badges for getting involved with the chats and the content-feedback activities. The researchers say it was clear that students were changing their behaviour once badges were made available: they were putting in the extra effort required to get their hands on these prizes. The study also found that those who were the first to pose queries on the forums tended to perform worse overall in the MOOC than those who were responding to those queries with helpful advice in the same discussion threads.

Again, I would argue that the idea of students putting in the extra effort when the activity is incentivized is a clear mirror of what occurs in the tradition classroom. In my primary school, I used to work extra hard for the shiny gold stars and in secondary school we used to be awarded paper credits for high achievement. Likewise, the idea of the smarter kids helping those who are struggling with the content is also a mirror of a harmonious classroom in the real world. To stretch my argument drastically, I am convinced that for most walks of life, behaviour on the Web is no different from the way we act in the real world. But that would take an entire book to justify, which I won’t bore you with here.

For more information about the rise of MOOCs, you can read my feature article “The MOOC point”, which appears in the March issue of Physics World. This special issue about education is available as a free PDF download. I also produced this short film about a new initiative at the Massachusetts Institute of Technology in which MOOC technologies are being incorporated into the traditional undergraduate physics programme. Take a look at that to discover what the students make of this new form of blended learning.

Fran Scott’s four golden rules for getting kids hooked on science

“Ever heard a child say ‘Yeah, I get it!’? Well, if you do, they’re lying. They’re only saying those words because you’re boring them and they don’t want to listen any more.”

That’s not me telling you – it’s Fran Scott, a BBC science presenter who has spent the last nine years involved in informal children’s science education, most recently working for Children’s BBC and BBC Learning.

Scott, who writes about her experiences in the March issue of Physics World magazine, finds “nothing more frustrating that the lazy communication of science”. And so, to help put things right, she has been involved in “many arms of science outreach”, including scientifically reviewing and advising on science books and also consulting on – and presenting – children’s science on the BBC.

In the article, Scott underlines how hard it is to really engage with children and distils her many years of experience into four golden rules. She advises you to remember them with the acronym “REAP”, claiming that they do reap great results. “I like rules,” says Scott. “They make you put the seemingly obvious into practice.”

Listed below are her four rules and a little bit about what they all mean, but to read the full article follow the links below.

Rule 1: Research – know the whole concept
Only by knowing as much as you can about the physics you want to explain can you interpret it and summarize it as a whole.

Rule 2: Extraction – select the key ideas
Boil down your knowledge to four to six bullet-pointed aspects, ideas or stories that together explain the whole principle you’ve researched.

Rule 3: Assimilate – boil down the ideas to one “learning outcome”
Collate your messages form rule 2 into one main idea that highlights the basis of all these principles.

Rule 4: Present – make your learning outcome engaging
Make your presentation entertaining, know what your audience knows, and do not use jargon unless you first explain it.

As Scott explains, if the rules seem obvious, it’s because they are. But they’re not so obvious that everyone adheres to them.

Members of the Institute of Physics (IOP) can read Scott’s full article in the March issue of Physics World magazine.

But remember that to get Physics World each month, simply join the IOP via this link.

Personal reflections on Plutopia

As Physics World’s reviews editor, I come across a lot of books that interest me intellectually. But with Kate Brown’s book Plutopia – the subject of this month’s Physics World podcast – my interest is personal, too.

Brown’s book tells the story of two cities, Richland in the US and Ozersk in the former Soviet Union, that were built to house workers at the nearby Hanford and Maiak plutonium plants. Brown calls these cities “plutopias” because high wages and subsidies meant that residents enjoyed a better standard of living than their neighbours outside the secure zones. Such benefits, in turn, fostered an atmosphere of loyalty and solidarity that helped keep the plants’ horrendous environmental records under wraps.

This sounded familiar to me because my childhood had a decidedly “plutopian” flavour.  Although I didn’t grow up in an “atomic city” like Richland or Ozersk, my father worked for a defence contractor for 39 years, and his plant’s generous vacation allowance meant that we took longer holidays than most American families. We had good health insurance, too, which may have saved my life as a teenager. But after reading Plutopia and speaking to Brown for the podcast, I found myself wondering whether such benefits were a fair trade for working, as my father and thousands of others did, in a mostly windowless building that was surrounded by razor wire and contaminated with beryllium dust.

Such hazards were, of course, small beer compared with those at Hanford and Maiak, both of which sent at least 200 million curies of radiation into the environment – twice the amount released in the meltdown at Chernobyl – during their 40-plus years of operation. How they managed to do this without anyone speaking out is a fascinating question, and toward the end of the podcast (which you can download or subscribe to via iTunes) you’ll hear Brown talking about the lessons she hopes physicists will learn from reading Plutopia.

Brown has some good recommendations for how physicists can help prevent future nuclear disasters, and I’d encourage you to listen to them. But in my case, her book’s biggest impact has been on how I regard my own family history.

Physicists link neutron stars to earthbound alloys

Neutron stars could share some unlikely similarities with metallic alloys here on Earth. That’s the conclusion of two physicists in Scandinavia, who have carried out calculations that reveal that the nuclei and neutrons in the outer crust of these stars play a similar role to the different metals in an alloy. The finding could provide insights into some observable properties of neutron stars, including gamma-ray bursts, rotational glitches and gravitational waves.

Neutron stars are dense spheres with a radius of just 11–12 km in which the gravitational pressure is so strong that the electrons have merged with protons to form a structure that is almost entirely composed of neutrons. Neutron stars are believed to have an outer crust about 1–2 km thick that behaves rather differently from the rest of the star. The crust is thought to contain protons that clump together with neutrons to form what are essentially neutron-rich nuclei, with the electrons forming a residual background charge.

As for the neutrons not bound to nuclei, these can move freely about the crust. The conventional view is that these free neutrons have little effect on the crust, the result being that the nuclei arrange themselves into the body-centred cubic (BCC) crystal structure favoured by many metals. However, Dmitry Kobyakov of Umeå University in Sweden and Chris Pethick of the Niels Bohr Institute in Denmark and NORDITA in Stockholm now argue that the free neutrons do play an important role in the crust.

Attractively drippy

The researchers focused on crusts with a density above which some neutrons are no longer bound in nuclei but “drip” out – the density at this threshold being about one thousandth that of a nucleus. According to their calculations, the free neutrons lead to an attractive interaction between the nuclei and that – under certain circumstances – makes the crystal unstable to distortions of the BCC lattice. This could in turn trigger a structural phase transition from BCC to a cubic lattice with two atoms per unit cell. This can be envisioned as the movement of the “body-centred” atom in the BCC unit cell towards the centre of a face of the cubic cell.

According to Kobyakov and Pethick, the crust can be thought of as a binary alloy with the nuclei and neutrons playing the roles of two different atomic species. The analogy with metallic alloys is important because many alloys can exist in a number of different structural phases that can have very different properties. A familiar example is iron, with pure iron having a BCC structure and stainless steel (iron and chromium) having a face-centred cubic structure and very different material properties.

Rich and varied structures

The implication of the work is that the crust of neutron stars could also have a rich and varied range of structural phases. As in alloys, the material properties of the crust – such as its propensity to crack or buckle – could be related to the presence of two or more structural phases. This information is of great interest to those studying neutron stars because the outward appearance of these objects is defined by the crust. It has been suggested, for example, that some features of observed energetic bursts of gamma rays could be attributed to shattering of the crust of a neutron star.

Moreover, as the crust plays a crucial role in transporting energy from the interior of the star out into space, knowing its properties would boost our understanding of how neutron stars cool. Greater knowledge of the crust could also help us to understand curious events called “glitches”, where the rotational speed of a neutron star suddenly increases. Some astrophysicists believe that glitches are related to ruptures of the cooling crust, while others argue that they are internal effects.

The strength of the crust is also important for determining the height of “mountains” on the surface. Such features could break the rotational symmetry of the fast-spinning neutron star, causing it to broadcast gravitational waves that could be detected by future detectors.

The calculations are described in Physical Review Letters.

Seismic cloak could minimize earthquake damage

Photograph of the seismic cloak test site
The seismic cloak was created by boring holes 5 m deep into the soil and its performance was tested using the vibration sensors that are arranged on the ground in front of the crane. (Courtesy: Stéphane Brûlé, Ménard)

Vulnerable buildings could someday be shielded from damaging earthquakes by surrounding them with “seismic invisibility cloaks”. An early prototype of such a cloak has been tested experimentally by researchers in France. In principle, the concept could be extended to create protective barriers that divert earthquake energy away from sensitive facilities such as nuclear power plants.

Traditional earthquake engineering is based on damping and dissipating the energy absorbed by a building when it is hit by shock waves. Now, computational physicist Sebastien Guenneau and colleagues at the Institut Fresnel and the geoengineering company Ménard have taken a different approach that involves modifying the ground around a building to divert seismic waves, effectively cloaking the structure from an earthquake’s destructive energy. They have also conducted preliminary field tests on the efficacy of the design for earthquake protection.

Their design is the latest extension of the concept of metamaterials, which were first suggested for electromagnetic waves in 1968 by Soviet physicist Victor Veselago. The first metamaterials were built in 2006 by a team that included John Pendry at Imperial College London and David Smith at Duke University in North Carolina. Pendry, Smith and colleagues created artificial materials with negative indices of refraction – properties that do not normally occur in natural materials. Pendry and others also developed a mathematical tool called transformation optics to describe how a metamaterial should be structured to have the desired properties.

Transformation seismology

The most famous application of transformation optics is the invisibility cloak, which guides electromagnetic waves around an object and so makes it appear to be invisible. In previous work, Guenneau and colleagues had shown that transformation optics transfers easily to seismology. While electromagnetic waves pass energy back and forth between the electric and magnetic fields, seismic waves pass energy between the potential energy stored in the deformation of the Earth’s crust and the kinetic energy contained in its movement. If the electric permittivity term is replaced by the soil density and the magnetic permeability by its elastic modulus, transformation optics becomes transformation seismology.

That is the theory, but actually making a practical cloaking structure that works for all destructive seismic waves is fiendishly difficult. This is because both the soil density and elastic modulus of the surroundings have to be controlled simultaneously. Furthermore, the elastic modulus needs to be different for deformations in different directions. Similar challenges faced the builders of the first electromagnetic cloaks, who worked around the problem by creating cloaks that worked in 2D rather than 3D. It turns out that this simplification also works for earthquake protection as most damage is caused by waves propagating directly across the Earth’s surface.

As a simple test of the hypothesis, Stéphane Brûlé and colleagues at Ménard buried a source vibrating at 50 Hz – the upper end of the frequency of earthquake surface waves – just below the surface of a sedimentary basin. Several metres away, sensors mapping the speed at which the earth vibrated recorded strong oscillations. The researchers then bored strategically placed, 5-m-deep holes to modify the density and elastic modulus of the soil, as they calculated would be necessary. With the holes in place, some regions on the other side of the boreholes recorded less than 20% of the oscillation amplitude, showing that the modified soil had indeed stopped much of the wave energy.

‘A completely new approach’

Pendry describes the research as “a completely new approach”, although he points out that the cloak would require similar space to the region being cloaked. “It’s not something you’re going to do in Manhattan,” he says. “On the other hand, it might be something you’d want to do if you had a very high-value strategic object such as a nuclear reactor.” Cloaking expert Andrea Alú also says the work is “neat”, but he sees a potential pitfall with the simple shield demonstrated here. “Whatever you don’t transmit, you reflect,” he says, “If you are in a crowded environment, you may cause problems for other buildings.”

The researchers openly acknowledge this limitation. They are currently building the full cloak, which should control the flow of waves, ensuring they do not damage neighbouring structures. Gunneau concludes the involvement of the Ménard civil-engineering company shows the research “is likely to have real applications”. “It’s not just for fun,” he says.

The research will be published in a forthcoming issue of Physical Review Letters.

China to build a huge underground neutrino experiment

Work has started on a huge underground neutrino lab in China. The $330m Jiangmen Underground Neutrino Observatory (JUNO) is being built in Kaiping City, Guangdong Province, in the south of the country around 150 km west of Hong Kong. When complete in 2020, JUNO is expected to run for more than 20 years, studying the relationship between the three types of neutrino: electron, muon and tau.

The design concept for the detector was completed last year and it will be built by the Institute of High Energy Physics (IHEP), which is part of the Chinese Academy of Sciences (CAS). JUNO will require an 80 m high and 50 m diameter experimental hall located 700 m underground. Its detector – filled with 20,000 tonnes of liquid scintillator – will use more than 15,000 photomultiplier tubes to detect the scintillation light that is created when a neutrino hits a hydrogen atom.

Big challenge

Although JUNO will be able to detect neutrinos produced by supernovae as well as those from Earth, the observatory will mainly study neutrinos created at two nearby nuclear power plants being built around 50 km from the experiment. “We need to detect neutrinos from the nuclear reactors, from a proper distance,” says Yifang Wang, IHEP director, who heads the JUNO project. “It will be a big challenge to build such a large underground lab and a detector in five years.”

The detector is expected to have an energy resolution of around 3%, allowing JUNO to determine the relative masses of the three kinds of neutrinos, known as the neutrino-mass hierarchy. Several similar experiments around the world – including NOvA in the US, Hyper-Kamiokande in Japan and the planned Indian Neutrino Observatory – will also work towards this goal. “That is an important part – to solve the mystery of why matter dominated over antimatter in our universe,” says Jun Cao, a particle physicist at IHEP.

Previous success

China’s experience operating the Daya Bay neutrino experiment for the last three years will stand it in good stead for JUNO. “The success of Daya Bay has attracted more potential foreign partners for JUNO,” adds Wang. Along with IHEP and 19 other Chinese institutions, interest in joining JUNO has also been expressed by more than 30 international institutions, including partners in Daya Bay from the Czech Republic, France, Germany, Italy, Russia and the US. “JUNO will help us build a leading research team, and make China one of the leaders in the field of particle physics,” adds Wang.

Plutonium’s toxic legacy

The cities of Richland and Ozersk were on opposing sides during the Cold War, but they have a lot in common. Richland, in eastern Washington state, was built as a “company town” for the Hanford nuclear reactor, America’s main plutonium-production facility. Ozersk, in the southern Ural Mountains, is its Russian counterpart – a “closed city” where, even today, most residents are connected in some way to the nearby Maiak plutonium plant.

Because these plants were vital to the US and Soviet nuclear-weapons programmes, workers at Hanford and Maiak got paid extremely well, and they and their families enjoyed a wide range of benefits. But as Kate Brown reveals in her book Plutopia, these privileges came at a terrible cost. Between the 1940s and the 1980s, the Hanford and Maiak reactors each released at least 200 million curies of radioactivity into the environment – twice as much as caused by the explosion at the Chernobyl nuclear reactor. The areas nearby are now some of the most polluted places on Earth.

In this podcast, you will hear Brown – an historian at the University of Maryland, Baltimore County – talking to Physics World reviews editor Margaret Harris about her research on these two “atomic cities” and what she hopes physicists will learn from their stories.

BICEP2 surprise visit, a bizarre rant, credible science fiction and more

 

By Hamish Johnston

The big story this week is that astronomers working on the BICEP2 telescope may have spotted the first direct evidence for cosmic inflation.  This is very good news for the physicist Andrei Linde, who along with Alan Guth and others did much of the early work on inflation. In the above YouTube video Linde, who is certainly in the running for a Nobel prize, receives a surprise visit from BICEP2 team member Chao-Lin Kuo. Kuo is the first to tell Linde and his wife, the physicist Renata Kallosh, the news that the theory that Linde developed more than 30 years earlier had finally been backed up by direct observational evidence. Not surprisingly, champagne glasses are clinking!

Here at physicsworld.com we have tried to tell both sides of the story: the thrill of seeing the first hints of cosmic inflation, tempered with calls for caution that more data are needed before inflation is victorious over other theories describing the early universe.

(more…)

Nanoparticles boost solar-energy capture by plants

Nanoparticles could increase the amount of solar energy captured by plants by as much as 30%. That is the conclusion of researchers at the Massachusetts Institute of Technology (MIT), who have shown that plants with semiconducting carbon nanotubes in their leaves can better convert energy from sunlight into electrical current.

The team believes that the discovery could be exploited in a new field dubbed plant “nanobionics”, whereby nanoparticles could enhance natural functions in ordinary plants and also be used to create artificial plant-like systems that grow and repair themselves using sunlight and water. Potential applications include biochemical detectors for monitoring pollutants in the environment and perhaps even new technologies that would help increase crop yields.

“Plants provide us with food and fuel, and even the oxygen we breathe, but they have been little used in technology applications until now,” says team member Juan Pablo Giraldo. “We are talking about a new field at the interface between nanotechnology and plant biology, which we have called plant nanobionics.”

Measuring electron flow

Led by Michael Strano, the team used two techniques to measure electron flow in plant leaves and chloroplasts in the lab. The first relied on measuring the changes in colour of a dye that intercepts electrons between the photosystems in chloroplasts extracted from plants. The second is based on monitoring changes in chlorophyll fluorescence in extracted chloroplasts and leaves. Chloroplasts are organelles inside a plant cell that use chlorophyll to capture and store the energy from solar radiation.

According to the MIT team, the nanotubes appear to enhance the amount of light absorbed by chlorophyll at wavelengths that are normally only weakly captured by plants. This includes green light as well as the ultraviolet and near-infrared parts of the electromagnetic spectrum. The result is that the nanoparticle-treated plant leaves can produce as much as 30% more photocurrent than non-treated plants.

The researchers also found that nanotubes combined with polymer nanoparticles containing ceria (a rare-earth metal oxide) act as “antioxidants”, and dramatically reduce the number of damaging oxygen radicals in extracted chloroplasts – something that could also help increase photosynthetic activity.

Self-repairing artificial plant-like systems

“Being able to enhance chloroplast photosynthesis with nanoparticles could allow us to develop artificial plant-like systems that would be powered by solar energy and be able to repair themselves like real plants,” says Giraldo. “Both these and the nanoparticle-augmented ordinary plants, might, for example, be used as biochemical detectors for monitoring pollutants, such as nitric oxide, in the environment. They might even be able to detect dangerous chemicals and gases, depending on the type of nanoparticle incorporated.”

The team says that it would now like to better understand how carbon nanotubes capture and transfer light energy to the photosynthetic machinery in plant chloroplasts. “The ultimate goal is to find out whether assembling chloroplasts with nanoparticles such as carbon nanotubes can help increase the amount of chemical fuels (such as glucose) that plants produce,” Giraldo explains. “Such studies will take our technology to a new level of applications, such as increasing crop yields or algae biofuel production.

“Ideally, we need remote-detection instruments that allow us to image in real time the near-infrared fluorescence changes of carbon nanotubes in plants under real-life conditions,” he adds.

The research is described in Nature Materials.

Could a canned UK-led telescope have discovered B-modes before BICEP2?

This week has seen physics news hit the mainstream in a way not seen since the Higgs boson was discovered at the CERN particle-physics lab in 2012.

On Monday, researchers working on the Background Imaging of Cosmic Extragalactic Polarization (BICEP2) telescope at the South Pole revealed that they have detected the first evidence for the primordial B-mode polarization of the cosmic microwave background (CMB). You can read our news stories about the finding here and here.

Yet could scientists in the UK have got there first if a telescope they had been planning to build – dubbed Clover – hadn’t been axed in 2009?

In 2007 UK physicists and astronomers were hit by a massive funding crisis that engulfed one of the country’s main funding agencies: the Science and Technology Facilities Council (STFC). The £80m black hole in the STFC’s budget forced the council to stop supporting research into the International Linear Collider, withdraw from the Gemini telescopes in Hawaii and Chile, as well as slashing grants for researchers in particle physics and astronomy.

The fallout from the crisis was felt for a number of years afterwards (some would say it still is today) and was followed by a host of “programmatic reviews”, which ranked projects against each other and sometimes resulted in the cancellation of lower-priority facilities.

Although Clover was actually deemed to be of “high importance” by the STFC in a 2008 review, it didn’t escape the chop, which happened in March 2009. The reason given by the STFC was because construction costs had risen by 60% to some £7.5m.

A collaboration between Cambridge, Cardiff, Manchester and Oxford universities, the UK-led telescope, which would have been located in the in the Atacama Desert in Chile, was designed to search for exactly what BICEP2 discovered this week.

Michael Jones, an experimental cosmologist at Oxford who was an instrument scientist for Clover, told physicsworld.com that while the BICEP2 results are “very exciting” but need to be confirmed by other telescopes, he bemoans the fact that Clover could have been one of those experiments now at the forefront of B-mode research.

“It was very clear back when Clover was cancelled that this day was going to arrive – everyone in the field recognizes the importance of the B-mode measurement, and everyone knew that when or if it was discovered, then it was going to be front-page news,” says Jones. “The fact that it seems to have been measured at such a high level means that Clover would definitely have been able to detect it. Of course, we can’t say whether or not Clover would have been first, but even if Clover hadn’t been first, it would have been part of what is now a highly important field.”

Of course, UK researchers are still involved in BICEP2, with Cardiff University a collaborating member of the telescope, and other experiments now in the hunt for B-modes such as Polarbear and the European Space Agency’s Planck mission.

But that seems scant consolation given the possibility that the UK might have got there first. “It is certainly worth pointing out that the STFC made the decision to pull the UK out of a field of unquestioned scientific importance, in which we had a leading position, to save what in retrospect seems to be quite a small amount of money,” adds Jones.

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