In 2010 I was using an all-new, no-textbook-in-class curriculum which I had developed during the summer. I decided to record all the classes so I could compare each lesson plan to the reality in the classroom. Within a day or so after a given class, I'd listen to the recording, and mark on the lesson plan what needed review, what I'd missed, etc. (For example, in last Wednesday's class, I forgot to introduce myself, and didn't discuss the inspiration of the Bible, even though both were in the lesson plan. Next week I'll take care of those items before beginning the new lesson.)
At year's end I had an mp3 file of each class, and moved the whole year onto an external drive. Every class is about 50mb; less than a mb/minute.
But there are other benefits which I wasn't aware of when I bought the thing:
1. If there's any "my child says the teacher said thus & so" heartburn, I have a record of what I said, and what the kids said. Heh. By the way, the sensitivity of the microphone and the quality of the sound are shockingly good.
2. Before this year's class I listened to last year's class; a terrific head start.
3. The recorder can do basic editing of the files. It's easy to split a 55 minute class into topical chunks, trim the getting settled/ roll-calling minutes from the beginning, and chatting from the end.
4. It names each new file with the date all by itself.
And the best thing about recording your classes:
5. To listen to yourself teach is a great way to refine your skills.
One problem I do have is that I forget to take the recorder with me after class. I tell the kids when class starts to remind me to pick it up and turn it off when class ends.