Science

Plant Seeds Do Something Incredible When the Sound of Rain Strikes (sciencealert.com) 4

"Plant seeds can sense the vibrations generated by falling raindrops," reports ScienceAlert, "and respond by waking from their state of dormancy to welcome the water, new research shows.... to germinate in 'anticipation' of the coming deluge." The finding, discovered by MIT mechanical engineers Nicholas Makris and Cadine Navarro, offers the first direct evidence that seeds and seedlings can sense and respond to sounds in nature... "The energy of the rain sound is enough to accelerate a seed's growth," [explains Markis].

Plants don't have the same aural equipment we do to actually hear sounds, of course. But the study suggests that seeds respond to the same vibrations that can produce a sound experience in our human ears. Across a series of experiments, the researchers submerged nearly 8,000 rice seeds in shallow tubs of water, at a depth of around 3 centimeters (1 inch), and exposed some of them to falling water drops over periods of six days... A hydrophone recorded the acoustic vibrations produced by the drops, confirming that the experiment mimicked the vibrations produced by actual raindrops falling in nature — such as the driving downpours that can sometimes pelt Massachusetts' puddles, ponds, and wetlands... In their study, the researchers observed that seeds exposed to the falling drops germinated up to around 37% faster, compared with seeds that did not receive the simulated rainstorm treatment but were housed in otherwise identical conditions.

More information in Scientific American and Scientific Reports.
Privacy

Fiber Optic Cables Can Eavesdrop On Nearby Conversations (science.org) 25

sciencehabit shares a report from Science Magazine: Cold War spies planted bugs in walls, lamps, and telephones. Now, scientists warn, the cables themselves could listen in. A fiber optic technique used to detect earthquakes can also pick up the faint vibrations of nearby speech, researchers reported this week here at the general assembly of the European Geosciences Union. Freely available artificial intelligence (AI) software turned the fiber optic data into intelligible, real-time transcripts. "Not many people realize that [fiber optic cables] can detect acoustic waves," says Jack Lee Smith, a geophysicist at the University of Edinburgh who presented the result. "We show that in almost every case where you use these fibers, this could be a privacy concern."

Fiber optics can pick up on sound through a technique called distributed acoustic sensing (DAS). Using a machine called an interrogator, researchers fire laser pulses down a cable and record the pattern of reflections coming back from tiny glass defects along the length of the fiber optic. When an earthquake's seismic wave crosses a section of the fiber, it stretches and squeezes the defects, leading to shifts in the reflected light that researchers can use to build a picture of an earthquake. DAS essentially turns a fiber cable into a long chain of seismometers that can detect not only earthquakes, but also the rumblings of volcanoes, cars, and college marching bands. And although scientists set up dedicated fiber lines specifically for research, DAS can also be performed on "dark fiber" -- unused strands in the web of fiber optics that runs through cities and across oceans, carrying the world's internet traffic.

DAS can also be used to eavesdrop, the work of Smith and his colleagues shows. They conducted a field test using an existing DAS setup used to study coastal erosion. They set a speaker next to the cable and played pure tones, music, and speech. Human speech contains frequencies ranging from a few hundred to several thousand hertz. The low end of the range could be pulled out of the data "even without any preprocessing," Smith says. "You can easily see acoustic waves." Getting higher frequency speech took a bit of postprocessing, but it was possible. Dumping the data directly into Whisper, a free AI transcription tool, provided accurate real-time transcription. However, this technique worked only for coiled cables, exposed at the surface, at distances of up to 5 meters from the speaker. Burying the cable under just 20 centimeters of dirt was enough to muddy the speech. And straight cables -- even exposed ones right next to the speaker -- did not record speech well.

Earth

NASA Keeps Track As Mexico City Sinks Into the Ground 25

An anonymous reader quotes a report from the Guardian: Walking into Mexico City's sprawling central Zocalo is a dizzying experience. At one end of the plaza, the capital's cathedral, with its soaring spires, slumps in one direction. An attached church, known as the Metropolitan Sanctuary, tilts in the other. The nearby National Palace also seems off-kilter. The teetering of many of the capital's historic buildings is the most visible sign of a phenomenon that has been ongoing for more than a century: Mexico City is sinking at an alarming rate. Now, the metropolis's descent is being tracked in real time thanks to one of the most powerful radar systems ever launched into space. Known as Nisar, the satellite can detect minute changes in Earth's surface, even through thick vegetation or cloud cover. "Nisar takes radar imaging observations of Earth to the next level," said Marin Govorcin, a scientist at Nasa's jet propulsion laboratory. "Nisar will see any change big or small that happens on Earth from week to week. No other imaging mission can claim this."

Though not the first time that Mexico City's sinking has been observed from space, the Nisar mission has provided a greater sense of how far the sinking spreads and how it changes across different types of land than any other space-based sensor. It has also been able to penetrate areas on the outskirts of the city that were previously challenging to study because of the complex terrain. The implications of the imagery extend far beyond the Mexican capital. "This study of Mexico City speaks to the realm of possibilities that will open up thanks to the Nisar system," said Dario Solano-Rojas, an engineer at the National Autonomous University of Mexico (Unam). "And not just for sinking cities but also for studying volcanoes, for studying the deformation associated with earthquakes, for studying landslides." According to Nasa, the technology is also capable of monitoring the climate crisis, glacier sliding, agricultural productivity, soil moisture, forestry, coastal flooding and more.
The Nisar system found that some parts of the city are dropping by more than 2cm a month. "First documented in 1925, the city's sinking is a result of centuries of exploitation of the groundwater," the report says. "Because Mexico City and its surrounds were built on an ancient lake bed, the soil beneath the city is extremely soft. When water is pumped out of the aquifer below, this clay-like earth compacts, resulting in a city that is quietly sinking."

The crisis is also self-reinforcing: as the city sinks, aging pipes crack and leak, causing Mexico City to lose an estimated 40% of its water, even as drought and climate change make supplies more fragile.
Medicine

Single Dose of Magic Mushroom Psychedelic Can Cause Anatomical Brain Changes 75

A small study found that a single 25mg dose of psilocybin produced measurable brain changes that were still visible a month later, along with reported improvements in psychological insight, wellbeing, and mental flexibility. The Guardian reports: Evidence for the changes came from specialized scans that measured the diffusion of water along nerve bundles in the brain. They suggested that some nerve tracts had become denser and more robust after the drug was taken. While the findings are preliminary, the scientists said the opposite was seen in ageing and dementia. "It's remarkable to see potential anatomical brain changes one month after a single dose of any drug," said Prof Robin Carhart-Harris, a neurologist at the University of California, San Francisco, and senior author on the study. "We don't yet know what these changes mean, but we do note that overall, people showed positive psychological changes in this study, including improved wellbeing and mental flexibility."

[...] Writing in Nature Communications, the researchers describe another key finding. Those who had the largest spike in brain entropy after psilocybin were most likely to report deeper psychological insight and better wellbeing a month later, underlining the link between flexible thinking and improved mental health. "It suggests a psychobiological therapeutic action for psilocybin," said Carhart-Harris. Prof Alex Kwan, a neuroscientist at Cornell University in New York, said studies in mice had shown that psychedelics can rewire connections between nerves, a form of "plasticity" that could underlie their therapeutic effects. The big question is whether the same occurs in humans. "This study comes closer than most to addressing that question, by giving evidence of lasting changes in brain structure after psychedelic use," he said. But while the results were "exciting," the study involved a small number of people and DTI provides an indirect and limited view of brain connections, he said.
Space

Astronomers May Have Detected an Atmosphere Around a Tiny, Icy World Past Pluto (apnews.com) 30

"The Associated Press is reporting on a new study in Nature Astronomy suggesting that a tiny, icy world beyond Pluto harbors a thin, delicate atmosphere that may have been created by volcanic eruptions or a comet strike," writes longtime Slashdot reader fahrbot-bot. From the report: Just 300 miles (500 kilometers) or so across, this mini Pluto is thought to be the solar system's smallest object yet with a clearly detected global atmosphere bound by gravity, said lead researcher Ko Arimatsu of the National Astronomical Observatory of Japan. This so-called minor planet -- formally known as (612533) 2002 XV93 -- is considered a plutino, circling the sun twice in the time it takes Neptune to complete three solar orbits. At the time of the study, it was more than 3.4 billion miles (5.5 billion kilometers) away, farther than even Pluto, the only other object in the Kuiper Belt with an observed atmosphere. This cosmic iceball's atmosphere is believed to be 5 million to 10 million times thinner than Earth's protective atmosphere, according to the the study [...].

It's 50 to 100 times thinner than even Pluto's tenuous atmosphere. The likeliest atmospheric chemicals are methane, nitrogen or carbon monoxide, any of which could reproduce the observed dimming as the object passed before the star, according to Arimatsu. Further observations, especially by NASA's Webb Space Telescope, could verify the makeup of the atmosphere, according to Arimatsu.

Space

Scientists Discover 27 Potential New Planets That Orbit Two Stars (theguardian.com) 11

Astronomers have identified 27 potential new circumbinary planets -- worlds that orbit two stars, like Star Wars' Tatooine. "To date, only about 18 circumbinary planets ... had been identified in the universe," reports the Guardian. "More than 6,000 planets have been discovered that orbit single stars, like Earth does around the sun." The Guardian reports: In a timely publication for May 4, also known as Star Wars Day, scientists have identified nearly 30 more candidate planets, whose distances range from 650 to 18,000 light years away from Earth. [...] More than half of the stars in the universe exist in binary or multiple star systems. The researchers instead used a method known as "apsidal precession," searching for a wobble between stars that orbit around and eclipse each other.

"If we monitor the exact timing of these eclipses ... that can tell us that there's something else going on in the system," said Margo Thornton, the study's lead author and a PhD candidate at UNSW. After eliminating other factors such as the rotation and gravitational pull of the two stars, the team identified 36 star systems out of 1,590 whose behavior could only be explained by a third body. For "27 of those objects, it is possible that they are planet mass," Thornton said.

More research into their spectra -- the light they emit -- was needed to formally confirm them as circumbinary planets, she said. "It's just a matter of: what is the mass of it? Is it a planet? Is it a brown dwarf? Is it a star?" The team discovered the potential planets -- which likely range from Neptune-sized to ten times heavier than Jupiter -- using data from Nasa's Transiting Exoplanet Survey Satellite, a planet-hunting space telescope that launched in 2018.
The research was published in the Monthly Notices of the Royal Astronomical Society.
Science

Infrasound Waves Stop Kitchen Fires, But Can They Replace Sprinklers? (reuters.com) 44

An anonymous reader quotes a report from Ars Technica: In a makeshift demonstration kitchen in Concord, California, cooking oil splatters in and around a frying pan, which catches fire on an unattended gas stove. Within moments, a smoke detector wails. But in this demonstration, something less common happens: An AI-driven sensor activates and wall emitters blast infrasound waves toward the source of the fire in an attempt to put it out. The science of acoustic fire suppression, which has long been known and documented in scientific literature and the press, works by vibrating oxygen molecules away from a fuel source, depriving the fire of a critical component needed for combustion. Indeed, after just a few seconds of infrasound, the tiny kitchen blaze goes out.

"We were able to not just point-and-shoot like a fire extinguisher; we figured out how to run it through ducting and distribute it like a sprinkler system," said Geoff Bruder, co-founder and CEO of Sonic Fire Tech, during the presentation. The company's goal is to replace sprinklers, which are effective at stopping fires but can also do significant water damage to a property. Sonic Fire Tech appears to be the first company trying to commercialize the science of acoustic fire suppression. Its executives have already been touring Southern California; Wednesday's event was the first in the northern half of the state.

The company aims to make this infrasound technique mainstream in both commercial (for instance, a data center, where sprinklers would damage electronics) and in-home installations, given that sprinklers are already required in all new California homes built in 2011 and later. Sonic Fire Tech also hopes to produce a backpack-based system that could be worn by wildland firefighters headed out into the field. "We are making meaningful technological improvements on a monthly basis," Stefan Pollack, a company spokesperson, emailed Ars after the event. But two experts who spoke with Ars raised serious questions about the potential for this technology to supplant traditional sprinklers in a home. They are even more skeptical as to whether the technique can be effective in an uncontrolled wildfire situation, where flames can grow very quickly.
Experts are concerned that infrasound may knock down small flames but does not cool hot surfaces or wet fuel like sprinklers do, which raises the risk of re-ignition, smoldering fires, hidden fires, or blocked fires. Sonic Fire Tech has claimed third-party validation and possible NFPA 13D equivalency, but it has not publicly released full testing details.

Fire officials and outside observers also want more information about reliability, maintenance, calibration, and how system failures would be detected and communicated.
Science

Carbon Pollution Is Making Food Less Nutritious, Risking the Health of Billions (detroitnews.com) 66

A new meta-analysis found nutrients in food decreased over the last 40 years, reports the Washington Post. "Many of humanity's most important crops — including wheat, potatoes, beans — contain fewer vitamins and minerals than they did a generation ago."

"The invisible culprit behind this damaging phenomenon? Carbon dioxide pollution." Surging concentrations of carbon in the atmosphere, caused largely by burning fossil fuels, have produced potent changes in the way plants grow — from increasing their sugar content to depleting essential nutrients like zinc... "The diets we eat today have less nutritional density than what our grandparents ate, even if we eat exactly the same thing," said Kristie Ebi, a professor at the University of Washington's Center for Health and the Global Environment.

People in wealthy countries with strong health care systems will have many tools to cope with the change, experts said. But for the world's poorest and most vulnerable, the consequences could be devastating. One study concluded that by the middle of the century the phenomenon could put more than a billion additional women and children at risk of iron-deficiency anemia — a condition that can cause pregnancy complications, developmental problems and even death. Meanwhile, some 2 billion people across the globe who already suffer from some form of nutrient shortage could see their health problems grow even worse. "The scale of the problem is huge," Ebi said.

Plants depend on carbon dioxide to perform photosynthesis — but that doesn't mean they grow better when there's more carbon in the air, scientists say. A sweeping survey of changes among 32 compounds in 43 crops found that nearly every plant that humans eat is harmed by rising CO2 levels... On average, they found, nutrients have already decreased by an average 3.2 percent across all plants since the late 1980s, when the concentration of carbon dioxide in the atmosphere was about 350 parts per million.

Thanks to long-time Slashdot reader GameboyRMH for sharing the news.
Science

Former NASA Engineers Create Ingenious Way To Save Homes From Wildfires Using Noise (nypost.com) 77

"Scientists have created a miraculous new way to stop fires from spreading through neighborhoods using nothing but sound," reports the New York Post: Former NASA engineers with California-based Sonic Fire Tech found that using sound waves can snuff out blazes and potentially be used to stop another Pacific Palisades inferno... The technology works by targeting oxygen molecules using low-frequency sound waves that vibrate them, stopping the fire from growing. "Sound waves vibrate the oxygen faster than the fuel can use it, and break the chemical reaction of the flame," Remington Hotchkis, Chief Commercialization Officer at Sonic Fire Tech told The Post.

The San Bernardino County Fire Department recently tested out the equipment using a backpack version and the results were incredible. Video shows firefighters fighting small blazes on a shrub and a stove top fire with the technology putting it out... In the home application, the system would be alerted/activated if there was a fire, sending the sound waves through a home duct system, essentially snuffing out the blaze. The sound waves can reach as far as 30ft from a home, the report noted. The sound is also harmless to pets and humans.

The article includes this quote that an executive at the company gave local news station KMPH. "Our former NASA engineers are rocket scientists, and they say it seems like magic, but it's just physics."
AI

An Amateur Just Solved a 60-Year-Old Math Problem - by Asking AI (scientificamerican.com) 93

Slashdot reader joshuark writes: Scientific American reports that a ChatGPT AI has proved a conjecture with a method no human had developed. A 23-year-old student Liam Price just cracked a 60-year-old problem that world-class mathematicians have tried and failed to solve.

The new solution that Price got in response to a single prompt to GPT-5.4 Pro was posted on www.erdosproblems.com, a website devoted to the Erds problems. The question Price solved — or prompted ChatGPT to solve—concerns special sets of whole numbers, where no number in the set can be evenly divided by any other...

Price sent it to his occasional collaborator Kevin Barreto, a second-year undergraduate in mathematics at the University of Cambridge. The duo had jump-started the AI-for-Erds craze late last year by prompting a free version of ChatGPT with open problems chosen at random from the Erds problems website. Reviewing Price's message, Barreto realized what they had was special, and experts whom he notified quickly took notice.

Medicine

Retina Scan for Diabetes Could Also Reduce Deaths During Pregnancy in Developing Countries (gatesnotes.com) 20

This week Bill Gates wrote a blog post about a special camera from medtech startup Remidio, which delivers high-resolution images of a patient's retina in seconds. The camera plugs into a phone running an AI system that watches for early signs of diabetes — all without needing a blood draw, eye dilation, or a dibetes specialist. It's already been used in 40 countries for more than 15 million patients. But that same hardware, with different software, can also flag the conditions that drive so many dangerous pregnancies. Gestational diabetes sharply increases the risk of pre-eclampsia [a spike in blood pressure during pregnancy responsible for half a million fetal deaths every year and 70,000 maternal deaths]... In most of rural sub-Saharan Africa or South Asia, it usually isn't screened for at all, because the standard test requires a lab. A retinal scan offers a different way in.

Remidio's device is currently being used in India to screen pregnant women for conditions that drive stillbirth. And researchers are now adapting the same hardware to screen for anemia and hypertension, too... [S]mall, portable, affordable diagnostics in the hands of community health workers are exactly the kind of lever that can start to move a number that hasn't moved in a long time.

Mars

New Lithium-Plasma Engine Passes Key Mars Propulsion Test (universetoday.com) 41

NASA engineers have tested a next-generation lithium-plasma electric propulsion system that reached 120 kilowatts, a new U.S. record and about 25 times the power of the electric thrusters on NASA's Psyche spacecraft. "Designing and building these thrusters over the last couple of years has been a long lead-up to this first test," said James Polk, who is a senior research scientist at NASA Jet Propulsion Laboratory. "It's a huge moment for us because we not only showed the thruster works, but we also hit the power levels we were targeting. And we know we have a good testbed to begin addressing the challenges to scaling up." Universe Today reports: While 120 kilowatts is a new record, NASA estimates it a future human mission to Mars will require 2 to 4 megawatts of power consisting of several thrusters and requiring more than 23,000 hours (958 days/2.6 years) of operation. To accomplish this, the thrusters would have to withstand more than 2,800 degrees Celsius (5,000 degrees Fahrenheit), which the thrusters achieved during testing.

The reason for the extended operation is due to the estimated time of an entire human mission to Mars, which is estimated to be approximately 2.6 years. This is because the launch window to Mars only opens once every two years due to the orbital behaviors of both planets. While no mission has ever returned from the Red Planet, this same launch window works from Mars to Earth, too. When launched within this window, robotic spacecraft have traditionally taken approximately 6-7 months to reach Mars.

However, a human mission would require a much larger spacecraft to accommodate the astronauts, food, fuel, water, and other mission-essential items. For the approximate 2.6-year mission, this would entail approximately 6-9 months traveling to Mars, followed by approximately 18 months on the surface of Mars until the next launch window opens, then another approximate 6-9 months back to Earth. However, having much less fuel due to the electric propulsion system could potentially alter this timeframe.

Medicine

In Real-World Test, an AI Model Did Better Than ER Doctors At Diagnosing Patients 82

A new study from Harvard Medical School and Beth Israel Deaconess found that an OpenAI reasoning model outperformed experienced ER doctors at diagnosing and managing patient cases using messy, real-world emergency department records. Researchers say the results don't support replacing doctors, but they do suggest AI could meaningfully reshape clinical workflows if tested carefully in prospective trials. NPR reports: The researchers ran a series of experiments on the AI model to test its clinical acumen -- including actual cases like the lupus patient who'd been previously treated at the emergency department at Beth Israel in Boston. The team graded how well the AI model could provide an accurate diagnosis at three moments in time, from the triage stage in the ER, up to being admitted into the hospital. Overall, AI outperformed two experienced physicians -- and did so with only the electronic health records and the limited information that had been available to the physicians at the time. "This is the big conclusion for me -- it works with the messy real-world data of the emergency department, " said Dr. Adam Rodman, a clinical researcher at Beth Israel and one of the study authors. "It works for making diagnoses in the real world."

Other parts of the study focused on case reports published in the New England Journal of Medicine and clinical vignettes to suss out whether the AI model could meet well-established "benchmarks" and game out thorny diagnostic questions. "The model outperformed our very large physician baseline," said Raj Manrai, assistant professor of Biomedical Informatics at Harvard Medical School who was also part of the study. The authors emphasize the AI relied on text alone, while in real life, clinicians need to attend to many other inputs like images, sounds and nonverbal cues when diagnosing and treating a patient.
The findings have been published Thursday in the journal Science.
China

Convicted Former Harvard Scientist Rebuilds Brain Computer Lab In China (reuters.com) 73

Reuters reports that Charles Lieber, the former Harvard scientist convicted of lying to U.S. authorities about payments and ties to China, is now leading China's state-funded i-BRAIN lab in Shenzhen, where he has access to advanced nanofabrication tools and primate research facilities for brain-computer interface work. From the report: Charles Lieber, 67, is among the world's leading researchers in brain-computer interfaces. The technology has shown promise in treating conditions such as ALS and restoring movement in paralyzed patients. But it also has potential military applications: Scientists at China's People's Liberation Army have investigated brain interfaces as a way to engineer super soldiers by boosting mental agility and situational awareness, according to the U.S. Defense Department. Lieber was found guilty by a jury and convicted in December 2021 of making false statements to federal investigators about his ties to a Chinese state program to recruit overseas talent, and tax offenses related to payments he received from a Chinese university. He served two days in prison and six months under house arrest, and was fined $50,000 and ordered to pay $33,600 in restitution to the Internal Revenue Service. During the case, his defense said he was suffering from an incurable lymphoma, which was in remission, and he was fighting for his life.

Three years after he was sentenced, Reuters has learned that Lieber is now overseeing China's state-funded i-BRAIN, or the Institute for Brain Research, Advanced Interfaces and Neurotechnologies, with access to dedicated nanofabrication equipment and primate research infrastructure unavailable to him at Harvard. The lab is an arm of the Shenzhen Medical Academy of Research and Translation, or SMART. "I arrived on April 28, 2025 with a dream and not much more, maybe a couple bags of clothes," Lieber said of his move to China at a Shenzhen government conference in December. "Personally, my own goals are to make Shenzhen a world leader."

SMART last year appointed Lieber as an investigator, according to a post on i-BRAIN's website dated May 1, 2025. That news was covered by some media outlets. The same day, i-BRAIN said Lieber had also been appointed its founding director -- an announcement that went unreported at the time. This story is the most comprehensive account of Lieber's activities since he moved to China. Reuters is reporting for the first time that his lab has access to dedicated primate research facilities and chip-making equipment; that it sits within a sprawling ecosystem of state-backed institutions bankrolled by billions of dollars in government funding; and that it is housed within an institution that is luring top scientific talent back from the United States.

Education

Should Schools Get Rid of Homework? (npr.org) 192

Tony Isaac shares a report from NPR: Federal survey data shows that the amount of math homework assigned to fourth and eighth grade students, in particular, has been steadily declining for the past decade. Some educators and parents say this is a good thing -- students shouldn't spend six or more hours a day at school and still have additional schoolwork to complete at home. But the research on homework is complicated. Some studies show that students who spend more time on homework perform better than their peers. For example, a longitudinal study released in 2021 of more than 6,000 students in Germany, Uruguay and the Netherlands found that lower-performing students who increased the amount of time they spent on math homework performed better in math, even one year later.

Other studies, however, suggest homework has minimal outcomes on academic performance: A 1998 study of more than 700 U.S. students led by a researcher at Duke University found that more homework assigned in elementary grades had no significant effect on standardized test scores. The researchers did find small positive gains on class grades when they looked at both test scores and the proportion of homework students completed. More homework was also associated with negative attitudes about school for younger children in the study. "The best educators figured out a long time ago that we can control what we can control," and that's what happens during the school day, Superintendent Garrett said, not homework. "There has been a shift away from it naturally anyway, and I felt like this made it equitable across our entire school system."
"The best argument for homework is that mathematical procedures require practice, and you don't want to waste classroom time on practice, so you send that home," said Tom Loveless, a researcher and former teacher who has studied homework.

Ariel Taylor Smith, senior director of the Center for Policy and Action at the National Parents Union, said: "The thing they point to is that it's an equity issue, and not all parents have the same availability and ability to support their students. I would make the argument that if a kid is really far behind in school, that's an equity issue. They need the additional time to practice." Kids, she said, "need more practice ... Sometimes, you do have to practice the boring stuff, like math."

"The interesting issue for folks to consider is not should there be more homework, but should there be better homework," said Joyce Epstein, who has studied homework and is the co-director of the Center on School, Family, and Community Partnerships at the Johns Hopkins University School of Education. "Better homework in math might be knowing the fact that kids don't have to be practicing for hours, 10 to 20 examples," when they could establish mastery in less time.

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