Decomposition is the result of the use of dead material (detritus or litter) as food by many different organisms. A common approach used by scientists interested in the factors that speed or slow the process is to use Alitter bags". These usually are made from screening and hold a standard amount of detritus. They can be placed in the environmentCsoil, stream, pond, etc. and then retrieved after a set amount of time and the fate of the detritus determined. Bags can be buried in different places, treated in different ways and/or filled with different materials. They also can be crafted from screening with different sizes of holes to allow different kinds of organisms to get to the detritus inside.
The instructions here are rather generic. They are intended to guide K-6 teachers to develop one or several investigations for or with their students to explore questions of their own interest.