You've probably seen this image making the rounds on social media. It shows a method of doing basic subtraction that's intended to appear wildly nonsensical and much harder to follow than the "Old Fashion" [sic] way of just putting the 12 under the 32 and coming up with an answer. This method of teaching is often attributed to Common Core, a set of educational standards recently rolled out in the US.
But, explains math teacher and skeptic blogger Hemant Mehta, this image actually makes a lot more sense than it may seem to on first glance. In fact, for one thing, this method of teaching math isn't really new (our producer Jason Weisberger remembers learning it in high school). It's also not much different from the math you learned back when you were learning how to count change. It's meant to help kids be able to do math in their heads, without borrowing or scratch-paper notations or counting on fingers. What's more, he says, it has absolutely nothing to do with Common Core, which doesn't specify how subjects have to be taught.
I admit it’s totally confusing but here’s what it’s saying:
If you want to subtract 12 from 32, there’s a better way to think about it. Forget the algorithm. Instead, count up from 12 to an “easier” number like 15. (You’ve gone up 3.) Then, go up to 20. (You’ve gone up another 5.) Then jump to 30. (Another 10). Then, finally, to 32. (Another 2.)
I know. That’s still ridiculous. Well, consider this: Suppose you buy coffee and it costs $4.30 but all you have is a $20 bill. How much change should the barista give you back? (Assume for a second the register is broken.)
You sure as hell aren’t going to get out a sheet of paper ...
Elenco’s Night ‘n Day Mechanical Globe uses a system of translucent, exposed gears to rotate an internally illuminated globe that displays the seasonally adjusted, real-time night/day terminator as it spins.
KSU plant biochemical geneticist Raj Nagarajan describes the properties of Thaumatin, Monellin and Brazzein, all found in west African plants that are generally considered safe for consumption; each is a protein, and they are, respectively, 1,000x, 2000x, and 3000x sweeter than sugar.
The amazing suckers on octopus arms aren’t just for sucking. They also are used to smell and taste. To deal with all that sensory input, the vast majority of an octopus’s brain cells are in its eight arms! “It’s more efficient to put the nervous cells in the arm,” neurobiologist Binyamin Hochner, of the Hebrew […]
Having a luxurious bed isn’t just a fairy tale from a catalog; it is a real, affordable possibility with offerings like this Olive+Owen bedroom set. If you’re thinking of doing some “spring cleaning”, this bed set is an easy way to completely upgrade your room in one purchase.This 20-piece collection has all of the expected slumberland elements, […]
Python is immensely popular in the data science world for the same reason it is in most other areas of computing—it has highly readable syntax and is suitable for anything from short scripts to massive web services. One of its most exciting, newest applications, however, is in machine learning. You can dive into this booming […]
Learning new skills is a great way to improve your resume and stand out from other candidates. Especially in a workforce in which many job-seekers have a wide variety of qualifications. With lifetime access to Virtual Training Company, you won’t have to choose a specific focus. You can pick up new expertise whenever you deem it […]