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This week we reached 10,000 subtitles across 50+ languages!  Congratulations to our dedicated volunteer translators.  We are inspired by their selfless contribution towards making quality education accessible for anyone anywhere.

While we’ve crossed a significant milestone, there is much that we can accomplish with your help towards providing a global educational resource.

Subtitling is as simple as 1-2-3:

1. Select ‘Options’ (below any video on www.khanacademy.org)
2. Select the ‘Translated subtitles’ option

You may have heard of (or even celebrated) Pi day on 3/14, but how about Tau day? What is Tau, you ask? In 2001, Bob Palais published the article "π Is Wrong" in which he argued that the beloved constant π is the wrong choice of circle constant. He instead proposed using an alternate constant equal to 2π, or 6.283… to represent “1 turn”, so that 90 degrees is equal to “a quarter turn”, rather than the seemingly arbitrary “one-half π”.

Two years ago today, Michael Hartl published "The Tau Manifesto" echoing the good points made by Palais and building on them by calling this “1 turn” constant τ (tau), as an alternative to π. Tau is defined as the ratio of a circle’s circumference to its radius, not its diameter and is equal to 2π.

Tau is approximately equal to 6.28, so that makes today (6/28) tau day! Aside from eating twice as much pie as we would on 3/14, we’ve found another way to recognize tau day: Thanks to Emily Eisenberg, one of our awesome summer interns, all of our exercises that can be answered in terms of pi can now be answered in terms of tau too!

All the hints and explanations still use pi, and of course we still accept answers with pi, but for those of you in the know, you can now use this secret feature to answer with tau!

Try it out for yourself, and let us know what you think!

Excerpted from an e-Literate post by Steven Zucker and Beth Harris, Khan Academy Deans of Art and History:

In many ways, scholarship at its best is conversation. But up until now, museums have conversed very little with one another—either on or offline.

Here is an example of how the Google Art Project opens the conversation. In 1889, Vincent van Gogh painted three canvases depicting his bedroom in Arles; these now reside in three different museums. Only the van Gogh Museum in Amsterdam illustrates another version on its website and remarkably, none of the three museums link to the paintings at the other institutions.

In contrast, the Google Art Project allows visitors to create and share a gallery where these paintings can be viewed side by side; it also includes links to their respective museum collections (where they exist). Imagine the educational impact if museums put together online galleries like this one and included commentary from curators at multiple institutions aimed at a non-scholarly audience.

To celebrate DNA Day (April 20), Khan Academy and 23andMe partnered together to make the 23andMe video series Human Prehistory 101 and Genetics 101 available on Khan Academy.

DNA Day commemorates the day in 1953 when James Watson, Francis Crick, and colleagues published papers in the journal Nature on the structure of DNA.

Press release from 23andMe

We are excited to announce our collaboration with MIT to develop more videos on science and engineering projects. Through a new initiative called MIT+K12, MIT students have produced videos focused on hands-on projects, simulations and historic experiments.

A selection of these videos are showcased on the MIT+K12 playlist. Videos include

More information on the MIT+K12 initiative can be found in this press release. Let us know what you think!