One of our local high schools emphasizes project-based learning. They claim this is superior to "book-learning", but I'm not convinced. Both have their uses, but project-based learning especially excels when breaking new ground. A typical high school education is merely a survey of Western knowledge, so the ground is well-trodden by now. 

I'm not skeptical of learning by doing; on the contrary, I wholeheartedly support it. 

I'm skeptical of any school that claims that their way of learning is the best. That kind of speech reeks of marketing and funding talking points, and I don't those who use it have the students' best interests at heart.

Languages are a perfect example of how project-based learning is a requirement of learning; book-learning doesn't suffice. The reason is because language is a two-way street. There are inputs and outputs. You must speak English and be able to understand English. You must be able to read and write to claim mastery of the written form.

To learn how to write, you must learn how to read. The more you read, the more information you have to pull from when writing. If you never write, it doesn't matter how much you read; you will never be fluent.

I learned Spanish without speaking Spanish. Now, I can only read Spanish. But I can't speak it, and speaking would have been a wiser focus when I was studying.

As I often say, I never wanted to learn how to code. I only wanted to make a game. So I learned how to code in order to make it. 

In this case, the project was the game. I had to learn a lot of things in order to make it. I didn't just learn coding; I learned animation, music production, and game design. Event better, I finally used a lot of the math I had learned throughout the years, too.

I support project-based and book-based learning. I don't think either approach alone is the best.

I think the problem that project-based learning schools are trying to solve is something else: a lack of student motivation. I said that I finally used the math I had learned when I made the game. In the meantime, all of that trigonometry was sitting in my brain, unused. However, I was able to finally use it because, at the time I was required to learn it, I was motivated to learn the trigonometry before I ever had a use for it.

 The project-based learning  schools are probably merely suffering from properly motivating students to learn. The real problem is motivation.