VOA标准英语2010年-Former Financial Analyst Teaches Math

A 33-year-old financial analyst¹ in California recently quit his job to devote himself to an unpaid² job teaching math on the Internet, and his lessons are reaching almost 100,000 people a month.  In this week's edition of Making a Difference, we introduce you to Salman Khan and his Khan Academy, and the difference they make for people who struggle to learn math.

Salman Khan's disembodied voice is heard every day - by tens of thousands of students around the world who are hungry for help learning math. He has posted 1,200 lessons on YouTube...lessons that appear on an electronic blackboard, and range from basic addition and advanced calculus³ to science and finance. And they are free.

"Introduction to Trigonometry is where I teach people about the trig functions," he explained. "This is one of the more popular videos. This has 179,000 views. And you know this is just what sine, cosine, and tangent are.

 

Salman Khan lives in California's Silicon⁴ Valley, with his wife, a rheumatologist in training at Stanford University, and their new baby. He got the idea for Khan Academy four years ago, when he taught a young cousin how to convert kilograms to grams. With Khan's help, the cousin got good at math, and Khan launched a new career.

Now, Khan records his lessons from a converted closet in the back of his bedroom. He never goes on camera.

"It kind of feels like my voice in their head. You're looking at it and feels like someone's over your shoulder talking in your ear, as opposed to someone at the blackboard, that's distant from you," he said.

When the all-girl Castilleja School in Palo Alto, California invited Khan to speak in person - he immediately connected to the students there.

The concept of short lessons that can be played over and over again attracted high school senior Bridget Meaney. She says she had trouble with seventh grade algebra⁵. "I think the teachers are good, but they can't go at a pace that's perfect for everyone," she said. "But I like the concept of knowing something in class but then going back and pressing pause or rewind and actually getting a deeper understand of it."

Originally, Khan kept his lessons short because of YouTube restrictions⁶. Now, he thinks short is better.

"I've gotten researchers  telling me that you don't realize 10 minutes [we've done studies] is how long someone can have a high level of concentration. And anything beyond that you kind of lose it. I think that we've all had that experience sitting in college where you can be with the professor for about 10 or 15 minutes and then you kind of lose it," he said.

For Khan, teaching math, science, and finance is just the beginning. He says he's ready to expand his YouTube site to include other subjects as well.
 

1 analyst   

n.分析家，化验员；心理分析学家

参考例句：

• What can you contribute to the position of a market analyst?你有什么技能可有助于市场分析员的职务？
• The analyst is required to interpolate values between standards.分析人员需要在这些标准中插入一些值。

2 unpaid   

adj.未付款的，无报酬的

参考例句：

• Doctors work excessive unpaid overtime.医生过度加班却无报酬。
• He's doing a month's unpaid work experience with an engineering firm.他正在一家工程公司无偿工作一个月以获得工作经验。

3 calculus   

n.微积分；结石

参考例句：

• This is a problem where calculus won't help at all.对于这一题，微积分一点也用不上。
• After studying differential calculus you will be able to solve these mathematical problems.学了微积分之后，你们就能够解这些数学题了。

4 silicon   

n.硅(旧名矽)

参考例句：

• This company pioneered the use of silicon chip.这家公司开创了使用硅片的方法。
• A chip is a piece of silicon about the size of a postage stamp.芯片就是一枚邮票大小的硅片。

5 algebra   

n.代数学

参考例句：

• He was not good at algebra in middle school.他中学时不擅长代数。
• The boy can't figure out the algebra problems.这个男孩做不出这道代数题。

6 restrictions   

约束( restriction的名词复数 )； 管制； 制约因素； 带限制性的条件（或规则）

参考例句：

• I found the restrictions irksome. 我对那些限制感到很烦。
• a snaggle of restrictions 杂乱无章的种种限制