This is a kind of a simple experiment to show children about decomposition process happened in our environment. This activity can be a useful activity to start dicussion about some of environmental topics (you can pick one of the topics below - or you can create it yourself)
First, we can find some leaves. Then we tie a line (a plastic, to mark position) to this leaves. Burried some of them in the backyard (a 5 to 10 cm deep is acceptable) and we will dig for it after some weeks.
We also do a same experiment in a jar contain clear water, and a jar contain mud (if you have a better place - like in the side of a river, just do it ^_^). Don't forget to make sure to have the line tied nicely, so we can easily know the location of our experiments (specially for the one in our backyard). For control, leave some leaves in open air.
Look for the result after 1, 2, and 3 weeks.
1. Which leaves gone earlier (decomposed faster)? Why? - relate the answer with bacteria, and some living creature that help decomposition process...
2. What will our environment looks if the decomposition process never happened in our world?
3. Do you have any idea how to make this decomposition process faster? - example answer : with adding more decomposer-bacteria, in more practical activity-like adding more soil (contain many bacteria in it), fertilizer (source of energy for the bacteria),...
-After this experiment, we also may discuss about humus layer, organic farming, making bio-fertilizer, economic value of bio-fertilizer,...(you go on)
-Do same experiment with anorganic matter to show how long it will take to decay - then we can talk about recycle products, environmental problem caused by anorganic matter (trash), healthy life and more...
Picture taken from http://farm4.static.flickr.com/3335/3509943070_255da84b73.jpg?v=0