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David Perry
Giant nerd. Avid programmer. Bitcoin enthusiast.
Giant nerd. Avid programmer. Bitcoin enthusiast.

David's posts

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"C# is a powerful laser rifle strapped to a donkey, when taken off the donkey the laser doesn’t seem to work as well."
"#C is an M1 Garand standard issue rifle, old but reliable... #Perl is a molotov cocktail, it was probably useful once, but few people use it now. #JavaScript is a sword without a hilt."

Question for other programmers with healthy meeting-avoidance habits: I keep trying to keep meetings short and sweet by keeping spoken content vague and high-level and requesting specifics in email followups, but so far I've only managed to get ONE email followup ever.

I'm usually playing some kind of support role and my ability to help this team depends on me knowing what kind of help they actually need - but I just can't spend all day hunting people down in IRC, Skype etc just to get an answer I've already asked them for.

What do you do to encourage email followups to actually happen?

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Because what are they gonna do, tear gas an old man in a wheelchair?

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Never thought of it this way but sure, I'll say I'm proud to be a white blood cell.
“Access to information is a critical currency of power.”

Well I feel like an idiot. All these years I've been playing +Minecraft all the lava-induced deaths and creeper-based structure damage... All this time I've been wishing for a "save game" button or some kind of checkpoint feature and I just found it, already installed on my computer, mocking me with its obviousness. I have now versioned my Minecraft worlds with Git.

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Finally got tired enough of unplugging a million things to do something about it. I got Thunderbolt to HDMI adapters for both monitors, a nice beefy USB hub and a simple audio splitter and mashed 'em all together with +sugru. The result is one giant meta-plug that I can connect and disconnect all at once. It works surprisingly well.
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Half way through the week!

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Why is the idea of teaching kids the underlying concepts behind math controversial? Sure, little Timmy needs to learn the algorithm this guy used to arrive at the answer quickly, but what good is memorizing an algorithm if you don't actually understand what it's doing? Teaching rote memorization of algorithms is a great way to ensure kids are confused as hell when they reach calculus.
Common Core Epic Fail!
#geekhumor   #math   #mathematics  

Also see appended edited comment below.

One father, who has an advanced engineering degree, couldn't figure out the approach used to calculate a math problem presented on his son's elementary homework assignment: “Jack used the number line below to solve 427 – 316. Find his error. Then write a letter to Jack telling him what he did right, and what he should do to fix his mistake.”

“Dear Jack, Don’t feel bad. I have a Bachelor of Science Degree in Electronics Engineering, which included extensive study in differential equations and other higher math applications. Even I cannot explain the Common Core mathematics approach, nor get the answer correct. In the real world, simplification is valued over complication. Therefore, 427 - 316 = 111. The answer is solved in under 5 seconds — 111. The process used is ridiculous and would result in termination if used. Sincerely, Frustrated Parent.”

Edited: I posted this as a silly joke I've seen floating around Facebook, but it's turned out to be an annoying political kind of serious debate issue, it seems. So I'll qualify this with a serious comment as well. Btw, it may just be an urban legend -- and it might not have anything to do with actual 'Common Core' curriculum problems.

First, I think teaching difference (or sum) of numbers as distance is useful, and in general anytime you can visualize something abstract in a concrete geometric way, you can get a better intuitive understanding of what the math is actual doing. This particular one isn't to scale. Btw, the error is obvious to me instantly: he forgot to count off the 1 ten and skipped it, and just subtracted the hundreds and the six ones, and so was off by 10 in the end, so he got 121 instead of the correct 111.  

I've taught negative numbers to 2nd graders by introducing them to vectors. One girl showed me a proof of how 3-5 was impossible: she put three of her pencils on her desk, and said, "I can take away one; I can take away 2; and I can take away all 3; but I can't take away 5 pencils when I start with 3 pencils. It's downright impossible." (Boy I wish I had a video of this to post to youtube -- she was awesome. )

So I responded that was a wonderful proof; but that the reason you don't hear older kids say "take away" and say "minus" instead, is that subtraction isn't really taking away -- rather, it's moving left on the number line. So I showed them that if you add, you can put arrows head to tail of the two numbers you are adding, and at the end is the sum. And subtracting, you are adding a "minus number" that points the other way. So I had her, and all of them try it again, on the number line on their desks. They complained, "but the number line stops at zero!" And I said, "in kindergarten, then don't even have a zero -- their number lines start with 1. Well, this is the real answer -- we extend the number line left, just as we do to the right, and now we have answers to all these kinds of problems."

And so that same girl did a new proof: "Ok, I draw an arrow to the right 3 spaces; and then at the pointy end of that arrow I draw an arrow pointing left 5 spaces for 'minus 5' and then at the end it's 'negative 2'. That's the answer." And I said, "you got it!" 

Hence, if the illustration is clear and understandable, I think the geometric version gives an intuitive sense of what you're doing. 'Upgrading' that little girl's (and her classmates') algorithm for subtracting was crucial to her intuitive understanding. That's what this pic is also trying to do, but it's just a bit confusing, that's all. The point of the visualization is to give you an understanding how the mat works: you don't want to solve problems that way. In general, I think that if you can demonstrate a visual proof of an arithmetic or algebraic equation, you can get kids to 'grok' what's going on much better. Btw, I also introduced them to multiplication as adding in two directions, making a rectangle, and then counting up the squares in the rectangle. Worked great. But again, that's a visual tool to sharpen intuitions; you wouldn't ever rely on solving problems that way, either.

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So this one's been making the rounds again. Want to know why it's nonsense and you shouldn't waste your time arguing about proper comma use?

Examine the following counter-argument:

"We invited the stripper, JFK, and Stalin."

"We invited the stripper, JFK and Stalin."

The first, "correctly" using the Oxford comma makes it appear that you sent invitations to a stripper named JFK as well as Stalin. This is because of the comma's vaguely defined use in English as a delineator and separator of all things.

The humorous "problems" often shown as examples of why one or the other method is correct are in reality just examples of very poorly formed sentences which should have their structure, not their comma use, repaired. The following is clearer than the above examples regardless of whether the serial comma is included:

"We invited JFK, Stalin[,] and the strippers."

As someone who most often writes for journalistic publications rather than scientific ones, the style guides I'm held to require the omission of the serial comma and I'm happy to report that with only a modicum of care taken in my sentence structure it has never once caused any confusion.

Use or omission of serial commas is a stylistic choice, not a grammatical one.
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