Two companies are now producing software that allows a voice recording of a classroom lecture to be synced with slides and later viewed on an iPod, according to the New York Times on Monday.

It's a better alternative than simply listening to a student's voice recording, and hastily written notes don't always capture all the teacher's presentation on the white board. It's a natural evolution, especially for students who already have an iPod, to marry the two media.

Server software combines the voice and presentation into a file that the student can download to the iPod later. Of course, when the class turns to heavy interaction between the students and professor, it may not work. However, for formalized lectures to a large class, it can be of value.

Tegrity, a Santa Clara, Calif. company, provides its solution to the University of Central Florida for about 300 classes a year. "Students don’t have to review the whole lecture," said Alfred Ducharme, an assistant dean. "They can type in key words on their computer, do a Google-like search, and open the lecture at that point."

Purdue University in Indiana is planning to use a system from Echo360, A Sterling, Va. company. That system also records slides and lectures for integrated playback on Zunes and some iPods, like the touch.

The driving force behind this innovation is students who are on-the-go, commuting, and wanting to be able to review the class notes whenever and wherever they are. That's what the iPod did for music and video, so it's a natural extension to the classroom, even if it does make some professors a little bit nervous about having their less than perfect classroom moments captured for all time.