閱讀難度：

America's most popular teacher doesn't work at Harvard University or a fancy prep school. In fact, he doesn't work in a school at all, but his lessons have been viewed more than 56 million times, US News and World Report reports.

Salman Khan, a former hedge fund manager, is the founder of Khan Academy, a free online learning platform with a library of more than 2,300 videos covering everything from basic algebra and differential equations to the Vietnam War.

Most videos are brief – anywhere from a couple of minutes to a half hour, depending on the subject.

Khan scrawls equations and writes down key terms on a computer program that simulates a chalk board as he explains them with a voiceover track.

（點(diǎn)擊《美國(guó)新聞與世界報(bào)道》網(wǎng)站查看原文）

美國(guó)數(shù)學(xué)的救世主

?????? 《美國(guó)新聞與世界報(bào)道》消息，美國(guó)現(xiàn)在最受歡迎的老師已經(jīng)吸引了56萬(wàn)人次觀看他的課程——他不是哈佛大學(xué)的老師，也并非來(lái)自知名補(bǔ)習(xí)學(xué)校，事實(shí)上，他根本就沒(méi)有在學(xué)校工作過(guò)。

?????? 薩爾曼?汗曾經(jīng)是一名對(duì)沖基金經(jīng)理，他創(chuàng)辦了免費(fèi)教育網(wǎng)站“汗學(xué)院”。迄今為止，汗學(xué)院網(wǎng)絡(luò)平臺(tái)上的視頻數(shù)量超過(guò)2300段，從小學(xué)的簡(jiǎn)單加法、大學(xué)微積分到講解越南戰(zhàn)爭(zhēng)，內(nèi)容非常廣泛。

?????? 大部分視頻都簡(jiǎn)單易懂，因?yàn)榭颇康牟煌?，視頻長(zhǎng)度從幾分鐘到半小時(shí)不等。

?????? 汗在計(jì)算機(jī)上模擬建一個(gè)黑板，在上面寫(xiě)方程式和畫(huà)草圖，另外還配有畫(huà)外音，對(duì)一些概念進(jìn)行講解。

(China.org.cn June 15, 2011)