[SaxonMilton]

What is the physical observation that one would make about anaerobic decomposition compared with aerobic decomposition?

[Arkcon]

Well, right in the name of each, these is an important indicator of the difference.  The task for you is to take the word, and translate it into a physical description.  Can you do this for us?  Perhaps this is a assignment connected to a lab experiment, so maybe you can translate your observations?  Figuring things out for yourself is the best way to learn.

[Babcock_Hall]

It would also help if you specified what was decomposing.  Possibly decomposition could even be replaced by another concept, such as catabolism.