The Value of Self-Paced Learning

Why do we expect a C student to have a shot of understanding the next concept when they have gaps on a more basic one? 


There are two layers to self-paced learning, from a Khan Academy point of view. One is the videos that students can watch at their own pace, and there’s also the exercise portion which the students get to complete at their own pace.  

I have learned that there is an academic term for this, which is mastery-based learning.  In a traditional model, what happens is we’re all sitting in a class together. There’s a lecture, we do some homework, some practice, and at the end of a week or at the end of a semester we get an exam.  And on that exam, maybe I get a 95, maybe you get an 80, and maybe you get a ‘C’ put on your forehead or your permanent transcript. I get an ‘A’.  I feel good about myself; you don’t feel so good about yourself.  And then we move on to the next concept, the concept that is going to build on what the assessment just recognized as both of us being deficient in.  You didn’t know 20 percent of it, and I didn’t know five percent.  And most of those assessments, frankly, don’t even measure everything you need to know.  

So there’s probably even a bigger gap than that 20 percent or my five percent.  But no one even questions this.  Why do we expect that C student to have a shot of understanding the next concept when they have gaps on a more basic one?  

So, our thought process is it's a waste of time for someone to move on to calculus if they don’t get algebra yet.  I’ve seen people who can’t recognize an algebra problem who have been through calculus and physics and all the rest and that’s because they didn’t master anything.

So what we’re saying on some level is radical but on another level it’s common sense. Before you learn a more advanced topic, master the more basic one.  Before you ride the unicycle, master the bicycle.  Before you juggle knives, juggle oranges.  It’s something that won’t cut you.

In this paradigm, students can watch the videos, and pause and repeat as much as they want. Now that we have the software and the exercises, we start the students at the most basic concepts and we give them as may as they need.  They’re computer generated problems and so they have do a million questions if they have to have a million questions. But they keep doing them until they get 10 in a row.  Until they show that they’ve mastered that little nugget, that little concept, then they move to the next concept.  

Our whole goal is so that students don’t end up in Calculus with gaps in Trigonometry and Algebra.  And what you see over and over again is students flunking out of math and algebra and calculus.  And they have good algebra teachers, they have good calculus teachers and these kids are hard working. They want to learn.  And no one can figure out what the problem is.  And the problem almost always is a gap that that student had in fourth grade or seventh grade math. It’s almost impossible to diagnose in an algebra or calculus classroom.

Sal Khan, Founder & Executive Director, Khan Academy, will be appearing at Techweek Chicago, on June 27, 2013.

Now is your chance to submit questions for Sal Khan to be asked at the event!

Please submit your questions in the comment section below. 

Click here for more information

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Researchers hope the technology will further our understanding of the brain, but lawmakers may not be ready for the ethical challenges.

Still from John Stephenson's 1999 rendition of Animal Farm.
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  • Researchers at the Yale School of Medicine successfully restored some functions to pig brains that had been dead for hours.
  • They hope the technology will advance our understanding of the brain, potentially developing new treatments for debilitating diseases and disorders.
  • The research raises many ethical questions and puts to the test our current understanding of death.

The image of an undead brain coming back to live again is the stuff of science fiction. Not just any science fiction, specifically B-grade sci fi. What instantly springs to mind is the black-and-white horrors of films like Fiend Without a Face. Bad acting. Plastic monstrosities. Visible strings. And a spinal cord that, for some reason, is also a tentacle?

But like any good science fiction, it's only a matter of time before some manner of it seeps into our reality. This week's Nature published the findings of researchers who managed to restore function to pigs' brains that were clinically dead. At least, what we once thought of as dead.

What's dead may never die, it seems

The researchers did not hail from House Greyjoy — "What is dead may never die" — but came largely from the Yale School of Medicine. They connected 32 pig brains to a system called BrainEx. BrainEx is an artificial perfusion system — that is, a system that takes over the functions normally regulated by the organ. The pigs had been killed four hours earlier at a U.S. Department of Agriculture slaughterhouse; their brains completely removed from the skulls.

BrainEx pumped an experiment solution into the brain that essentially mimic blood flow. It brought oxygen and nutrients to the tissues, giving brain cells the resources to begin many normal functions. The cells began consuming and metabolizing sugars. The brains' immune systems kicked in. Neuron samples could carry an electrical signal. Some brain cells even responded to drugs.

The researchers have managed to keep some brains alive for up to 36 hours, and currently do not know if BrainEx can have sustained the brains longer. "It is conceivable we are just preventing the inevitable, and the brain won't be able to recover," said Nenad Sestan, Yale neuroscientist and the lead researcher.

As a control, other brains received either a fake solution or no solution at all. None revived brain activity and deteriorated as normal.

The researchers hope the technology can enhance our ability to study the brain and its cellular functions. One of the main avenues of such studies would be brain disorders and diseases. This could point the way to developing new of treatments for the likes of brain injuries, Alzheimer's, Huntington's, and neurodegenerative conditions.

"This is an extraordinary and very promising breakthrough for neuroscience. It immediately offers a much better model for studying the human brain, which is extraordinarily important, given the vast amount of human suffering from diseases of the mind [and] brain," Nita Farahany, the bioethicists at the Duke University School of Law who wrote the study's commentary, told National Geographic.

An ethical gray matter

Before anyone gets an Island of Dr. Moreau vibe, it's worth noting that the brains did not approach neural activity anywhere near consciousness.

The BrainEx solution contained chemicals that prevented neurons from firing. To be extra cautious, the researchers also monitored the brains for any such activity and were prepared to administer an anesthetic should they have seen signs of consciousness.

Even so, the research signals a massive debate to come regarding medical ethics and our definition of death.

Most countries define death, clinically speaking, as the irreversible loss of brain or circulatory function. This definition was already at odds with some folk- and value-centric understandings, but where do we go if it becomes possible to reverse clinical death with artificial perfusion?

"This is wild," Jonathan Moreno, a bioethicist at the University of Pennsylvania, told the New York Times. "If ever there was an issue that merited big public deliberation on the ethics of science and medicine, this is one."

One possible consequence involves organ donations. Some European countries require emergency responders to use a process that preserves organs when they cannot resuscitate a person. They continue to pump blood throughout the body, but use a "thoracic aortic occlusion balloon" to prevent that blood from reaching the brain.

The system is already controversial because it raises concerns about what caused the patient's death. But what happens when brain death becomes readily reversible? Stuart Younger, a bioethicist at Case Western Reserve University, told Nature that if BrainEx were to become widely available, it could shrink the pool of eligible donors.

"There's a potential conflict here between the interests of potential donors — who might not even be donors — and people who are waiting for organs," he said.

It will be a while before such experiments go anywhere near human subjects. A more immediate ethical question relates to how such experiments harm animal subjects.

Ethical review boards evaluate research protocols and can reject any that causes undue pain, suffering, or distress. Since dead animals feel no pain, suffer no trauma, they are typically approved as subjects. But how do such boards make a judgement regarding the suffering of a "cellularly active" brain? The distress of a partially alive brain?

The dilemma is unprecedented.

Setting new boundaries

Another science fiction story that comes to mind when discussing this story is, of course, Frankenstein. As Farahany told National Geographic: "It is definitely has [sic] a good science-fiction element to it, and it is restoring cellular function where we previously thought impossible. But to have Frankenstein, you need some degree of consciousness, some 'there' there. [The researchers] did not recover any form of consciousness in this study, and it is still unclear if we ever could. But we are one step closer to that possibility."

She's right. The researchers undertook their research for the betterment of humanity, and we may one day reap some unimaginable medical benefits from it. The ethical questions, however, remain as unsettling as the stories they remind us of.

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