There are a lot of reasons you may want to record in your classroom: assessment, auditions, and student portfolios are just a few of the possibilities. When I record in the classroom, I'm not looking for super high quality, CD worthy recordings. I want to use inexpensive (free is better) equipment and software. I want the process to be as simple as possible. I have done some recording in my classroom in the past. I've recorded a whole class singing so that we could evaluate the performance and figure out areas of improvement. I've recorded individuals who were interested in solos or special parts. This year, I'm hoping to record each student individually at least once in the school year. For the younger students, it will be a recording of their singing. For the older students, it may be recorder playing. Here are two of the recording tools I use in my classroom.
Audacity - This is a free software program that is available for Mac or Windows. Be sure to download and install the LAME encoder as well so that you are able to export your recordings as .mp3 files. I don't use a fancy microphone for my recordings. I've actually used a microphone that is intended for the SmartMusic program. I'm sure you can get something fairly inexpensive at your local electronics store. If you really want to get technical, unidirectional mics are for recording individuals and omnidirection mics are for recording groups. I pay little attention to that for my recordings in the classroom. Besides using Audacity for recording in the classroom, it has a bunch of other uses. I've used it to slow the tempo of an accompaniment without changing the pitch. I've used it to remove the vocal track on a split-track recording. I've used it to record voice-over dance calls with dance music for use by a sub (or in the case that I lose my voice).
Blue FiRe - This is a free app for the iPad. This worked well when I was recording students who were auditioning for a solo. After recording, the app assigns a temporary URL you can access on your computer and download the files. I just used the built-in mic from the iPad. This app is very user-friendly.
I think it would be really fun to record students each year and then share the recordings with them as they are getting ready to leave elementary school. Whether or not I can be that organized remains to be seen.