阅读难度：

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.

（点击《美国新闻与世界报道》网站查看原文）

美国数学的救世主

       《美国新闻与世界报道》消息，美国现在最受欢迎的老师已经吸引了56万人次观看他的课程——他不是哈佛大学的老师，也并非来自知名补习学校，事实上，他根本就没有在学校工作过。

       萨尔曼•汗曾经是一名对冲基金经理，他创办了免费教育网站“汗学院”。迄今为止，汗学院网络平台上的视频数量超过2300段，从小学的简单加法、大学微积分到讲解越南战争，内容非常广泛。

       大部分视频都简单易懂，因为科目的不同，视频长度从几分钟到半小时不等。

       汗在计算机上模拟建一个黑板，在上面写方程式和画草图，另外还配有画外音，对一些概念进行讲解。

(China.org.cn June 15, 2011)