The Talent Code

Instead, the teachers and coaches I met were quiet, even reserved. They were mostly older; many had been teaching thirty or forty years. They possessed the same sort of gaze: steady, deep, unblinking. They listened far more than they talked. They seemed allergic to giving pep talks or inspiring speeches; they spent most of their time offering small, targeted, highly specific adjustments. They had an extraordinary sensitivity to the person they were teaching, customizing each message to each student’s personality.

On John Wooden: Gallimore and Tharp recorded and coded 2,326 discrete acts of teaching. Of them, a mere 6.9 percent were compliments. Only 6.6 percent were expressions of displeasure. But 75 percent were pure information: what to do, how to do it, when to intensify an activity.


Online teaching vs. Classroom teaching


  • If teachers were to teach as Salman Khan teaches in his videos they would be down rated. The math teacher who shows her class several very clear examples followed by some practice problems will be rated developing on the basis that she was too teacher centered, not engaging, and too focused on procedures.
  • Where was the student engagement? Why weren’t they sitting in groups? Where was your differentiation? Where was your student-centered instruction? Why no discovery based learning?




Learning Myths

  • Quizzing yourself on something you’ve just read is a great example of active learning, the best way to learn.
  • Research shows that deep subject matter expertise is a key element in helping teachers excel.
  • What is helpful is that [the feedback] comes close to when you perform the task, and that it requires you to generate an answer
  • Re-reading and highlighting are particularly ineffective. They’re just passive, and you are just kind of skimming that material.   If you’re preparing for a meeting, you’d be much better off just putting the material away and just asking yourself questions.
  • I think there’s so much stuff out there now that’s like, “Learning’s supposed to be easy, learning’s supposed to be fun!”
  • People underestimate how much they forget, and people who are able to revisit their learning at a regular rate end up learning a lot more.


The 10,000-hour rule is wrong and perpetuates a cruel myth


  •  For example, the number of hours of deliberate practice to first reach “master” status (a very high level of skill) ranged from 728 hours to 16,120 hours. This means that one player needed 22 times as much deliberate practice as another player to become a master.
  •  Deliberate practice left more of the variation in skill unexplained than it explained. For example, deliberate practice explained 26% of the variation for games such as chess, 21% for music, and 18% for sports.
  • Researchers found that there was a stronger correspondence in drawing ability for the identical twins than for the fraternal twins. In other words, if one identical twin was good at drawing, it was quite likely that his or her identical sibling was, too.
  • But it does imply that there are limits on the transformative power of practice. As Mosing and her colleagues concluded, practice does not make perfect.
  •  Jesse Owens, Marion Jones, and Usain Bolt, and found that, in all cases, they were exceptional compared with their competitors from the very start of their sprinting careers — before they had accumulated much more practice than their peers.

Slate  BI



Investment Returns and Geometric Mean

What if an investment returned 5%, 20%, and 50% over three years?
Year 1:  $100 * .05 = $105
Year 2:  $105 * .20 = $126
Year 3:  $126 * .50 = $189

What was the annual return?  Can you just average the percentages?
Let’s try it.  The average of 5%, 20%, and 50% is 25%
Did you average 25% a year?

Year 1:  $100 * .25 = $125
Year 2:  $125 * .25 = $156.25
Year 3:  $156.25 * .25 = $195.31

No, 25% for 3 years gets you a different amount!

You calculate the average annual return via the geometric mean (not the arithmetic mean)

\sqrt[3]{1.05 * 1.20 * 1.50} -1 = .236

Your annual return was actually 23.6% 

Year 1:  $100 * .236 = $123.6
Year 2:  $123.6 * .236 = $152.77
Year 3:  $152.77 * .236 = $188.82



  • How much did practice actually explain? A 2014 meta-analysis looked specifically at the relationship between deliberate practice and performance in music, games like chess, sports, education, and other professions.
  • For some things, like games, practice explained about a quarter of variance in expertise.
  • For music and sports, the explanatory power accounted for about a fifth.
  • But for education and professions like computer science, military-aircraft piloting, and sales, the effect ranged from small to tiny. For all of these professions, you obviously need to practice, but natural abilities matter more.

Studies show taking notes by hand is more effective

Take Notes by Hand for Better Long-Term Comprehension

  • The results revealed that while the two types of note-takers performed equally well on questions that involved recalling facts, laptop note-takers performed significantly worse on the conceptual questions.
  • The benefit of having more content is canceled out by “mindless transcription.”
  • The amount of verbatim overlap was associated with worse performance on conceptual items.

What You Miss When You Take Notes on Your Laptop

  • Mueller and Oppenheimer predicted that the decrease in retention appeared to be due to “verbatim transcription.”
  • And again, though the laptop note takers recorded a larger amount of notes, the longhand note takers performed better on conceptual, and this time factual, questions.

A Learning Secret: Don’t Take Notes with a Laptop

  • Students who used longhand remembered more and had a deeper understanding of the material

Attention, Students: Put Your Laptops Away

Attention, Students: Put Your Laptops Away

  •  For questions that asked students to simply remember facts, like dates, both groups did equally well.
  • But for “conceptual-application” questions, such as, “How do Japan and Sweden differ in their approaches to equality within their societies?” the laptop users did “significantly worse.”
  • “The students who were taking longhand notes in our studies were forced to be more selective — because you can’t write as fast as you can type. And that extra processing of the material that they were doing benefited them.”

What percentage of these cars came with a stick shift?

I noticed a for sale ad for a 1996 Mustang, and was struck by the $3500 price… ’94-‘04 Mustangs seem like a great bang for the buck:  They are cheap, plentiful, have lots of parts available, and there’s lots of online DIY support.  Perfect for a student or hobbyist on a budget.

I opened up 35 ads and noticed 19 were manual.     I realized I was staring at a confidence interval problem!  

The Network Effect

If you have the only cell phone in the world, it’s pretty useless, since you can’t call anyone. If there are 2 cell phones, there is one possible connection.  If there are 3 cell phones, you can make a total of 3 connections.  4 cell phones can have a total of 6 connections.  5 cell phones?  10 connections.   6 phones means 15 connections.

The more devices there are, the most connections you can make.  The more connections there are, the more useful the whole network becomes.  This is also called Metcalf’s Law.

Let’s look at the sequence of numbers generated above.

1, 3, 6, 10, 15, …

Can you see the pattern?   The number of connections can be represented by \frac{n(n-1)}{2}  where n is the number of nodes in the network.  Notice that this is very similar to \frac{n^2}{2} = \frac{1}{2}n^2.  So, the number of total possible connections is proportional to the square of the number of nodes in the network.  

Most developers have never seen a successful project

Most developers have never seen a successful project

Is this bad science?  Since this is a retrospective study, there is non-random assignment for the treatment and control groups.  That introduces selection bias.  Projects that are more likely to implement a (long-winded) “waterfall” life-cycle approach are probably larger scale projects to begin with.  Correlation is not causation.  So, maybe it’s not the lifecycle approach that is the problem, but the confounding/lurking variable of project scale that is the problem.  The study should control for the size of the project to make a valid conclusion about success rate of the development approach used.  ie:  Building a large insurance processing system will use a lifecycle approach, while building a fitness app will not.  Apples to oranges, since one is much easier to be implement than the other.

Teacher Must Remain a Student

I write for the unlearned about things in which I am unlearned myself… It often happens that two schoolboys can solve difficulties in their work for one another better than the master can… The fellow-pupil can help more than the master because he knows less. The difficulty we want him to explain is one he has recently met. The expert met it so long ago that he has forgotten… I write as one amateur to another, talking about difficulties I have met, or lights I have gained…     -C.S. Lewis

Gimmicky Bidding Websites (Series/Sequence)

The way this site works is that if you bid, you have to pay that amount, even if you lose.  Bids are incremented by 1 cent.   Let’s say an item sells for 10 cents.  The guy who bid 1 cent still has to pay that, the guy who bid 2 cents still has to pay that, and so forth.   So, what does the auction site actually earn for selling that item for 10 cents?

Notice that 1+2+3+4+5+6+7+8+9+10  can be added up by grouping numbers from the opposite ends:  (1+10) + (2+9) + (3+8) + (4+7) + (5+6)   This is just 11+11+11+11+11  or 11*5 = 55.  Note that when x = 10, and we ended up multiplying 11*5 for the series sum.

So, the general formula is:

1 + 2 + 3 + … + n = \displaystyle\sum\limits_{x=0}^n x = (n+1)\frac{n}{2} = \frac{n^2+n}{2} = \frac{n(n+1)}{2}

Pop Quiz!  If the sunglasses in the photo end up selling for $6.96, how much does the website make?  \frac{696*697}{2} = \frac{485112}{2} = 242556 = \$2,425.56   !!

Can Students Have Too Much Tech?

  • “Students who gain access to a home computer between the 5th and 8th grades tend to witness a persistent decline in reading and math scores,” the economists wrote, adding that license to surf the Internet was also linked to lower grades in younger children.
  •  What’s worse, the weaker students (boys, African-Americans) were more adversely affected than the rest. When their computers arrived, their reading scores fell off a cliff.
  •  With no adults to supervise them, many kids used their networked devices not for schoolwork, but to play games, troll social media and download entertainment. (And why not? Given their druthers, most adults would do the same.)
  • Technology does have a role in education. But as Randy Yerrick, a professor of education at the University at Buffalo, told me, it is worth the investment only when it’s perfectly suited to the task, in science simulations, for example, or to teach students with learning disabilities.

Can Students Have Too Much Tech?