khan-academy-zh

1. The Website That Changed Bill Gates' Child

You may have heard the story: Bill Gates' child was struggling with math. Instead of hiring an expensive tutor, Gates used free videos recorded by a man named Salman Khan.
Gates famously said, "This guy did what the education world has been trying to do for years."

This is Khan Academy.
It’s not a business; it’s a non-profit with a massive mission: "A free, world-class education for anyone, anywhere."

2. Core Concept: What is "Mastery Learning"?

Traditional schooling is like "Swiss Cheese":
The class moves on to Geometry next week regardless of whether you understood 80% or only 50% of Algebra. The result? Gaps (holes) in your knowledge base that eventually lead to failure in advanced topics.

Khan Academy advocates "Mastery Learning":

• No Gaps: You don't move to the next level until you get a streak of correct answers on the current concept.
• Knowledge Map: The system visualizes your skill tree. You can instantly see what you've mastered (Dark Blue) and what you're missing (Grey).

3. How to Use It Effectively?

① The Math Savior (K-12 to University)
This is Khan's superpower.

• For Students: If you missed a concept in 8th grade, it will haunt you in high school Physics. Khan allows you to go back and plug that specific gap in an afternoon.
• For Adults: Want to get into AI but forgot Calculus? The Calculus courses here are intuitive and visual.

② Science & Computing

• Science: Physics, Chemistry, Biology. The videos use a digital blackboard style that is engaging and easy to follow.
• Computing: Computer Science principles and the famous "Hour of Code". Perfect for absolute beginners.

③ Gamification
Earning "Energy Points" for every video watched and problem solved makes learning addictive. You can unlock badges and evolve your avatar.

4. Pros and Cons

Feature	Pros	Cons	Advice
Cost	Free Forever, No Ads	None	For everyone
Quality	World-class pedagogy, focus on intuition	Simple production style (no fancy CGI)	Focus on the logic
Localization	Math/Science fully translated	Some Arts/Humanities still English-only	Use subtitles
Mode	Self-paced	Requires self-discipline	Set weekly goals

5. Conclusion

Khan Academy is the best manifestation of the internet's potential.
It eliminates the wealth gap in education, allowing a child in a remote village to access the same quality of explanation as a student at Harvard.
If you feel your math foundation is shaky or want to rekindle a love for science, open it now. Here, no one judges you for learning slowly; the system just waits for you to master it.