Podcasts

Traditionally, a podcast is a recording of a person talking on some subject.  If you go and find one on something like you tube or iTunes, you'd find that many are more casual conversations about a topic, ranging from important things like science, religion, politics, and history to things like video games, the best fishing lures or a presenters favorite sandwich.  So, we can say that they are a varied tool that fit many different subjects.

When it comes to a traditional podcast, it's usually a one or more person conversation with little to no scripting, just a flow of consciousness about a topic.  In a class room situation you will need to keep the topics more focused and narrow onto a specific science topic.  For example, let’s say we are using plant stages.  It wouldn't be a hard task to divide students into small groups for such an activity.  It also would not be a bad idea to ask for either a script or a bullet list of points the students want to talk about as important.  I would even suggest that the students find and use pictures to go along with what they are talking about, even though a podcast is usually just an audio recording.
Using this in class is rather easy, as many schools, if not the vast majority either have some access to laptops or ipads or some device with the necessary software.  That software being the free movie maker software you can get with any apple or PC.  Most all of them also have some kind of microphone, and if not a microphone can be bought for very cheaply and still deliver decent sound quality.  Much of the software is designed to be very user friendly and there are countless written instructions as well videos. 
Overall, podcasts are useful for conveying information in a casual tone.  They have the advantage of being primarily auditory so students can do some degree of editing to keep their points concise and appropriate.  A video requires a lot more planning and time outside of class or time inside class to film, along with more technology.  A podcast is simple and easy to do, and can be easily shared with the other students to be used as a kind of study guide.