If any undergraduate in Philip Greenspun's class skipped his most recent lecture, they're really regretting it.

The researcher at the Massachusetts Institute of Technology gave $100 to each of the four undergraduates at a computer science seminar he taught Thursday night. He did it to refund what he estimated was the cost of the class for the students, who he says are charged too much tuition."I'm not going to participate in the MIT tuition collection system," Greenspun said to gasps from the students. "I'll be happy to teach you, and I'll do my best, but I'm not going to take your money."

One of the bewildered students, 21-year-old computer science major Patrick McCormick, said he thought the gesture was a joke.

But after class, McCormick said admiringly: "He's a pretty passionate guy. He's willing to act on what he believes."

Greenspun said he handed out his own money. The MIT alumnus has founded five high-technology companies, written a book and works as a Web service designer. He posts the book on the Internet for anyone to copy, free.

Greenspun said MIT should drop its $23,100 tuition because the school produces well-trained, intelligent graduates for corporations and the government. They ought to pay, he said.

MIT spokesman Ken Campbell said the anticipated cost of educating each student is more than twice the actual tuition price, and more than half of all students get financial aid.

For other students, Campbell said: "Yes, (tuition) is high. On the other hand, you have to figure out what that education will get you at the end of four years, which is generally a very, very good job."