It so happened the my son was sitting though one "boring" church service and paging through a magazine called The Banner. It was the August 2011 one. This publication has a section called, "Just for Kids," and this particular month's was all about the rainforest (Really Cool Rainforests by a Mrs. Baker).
There was one part in it called Rainforests in a Bottle, and E decided in church that he better go home and make one. So. . .that is what he did (with a little help from Dad!)
They took a 2L pop bottle, cut it in half, put rocks in the bottom, and covered it with potting soil, just like the directions said to do. They added water to moisten the soil, and put a small strawberry plant inside. Then they attached the "top" of the bottle using clear packing tape.
The directions said to put it out in the sunshine, and that no more water was needed because the water inside the bottle recycles itself and the plant should grow. (See all the droplets on the sides of the bottle?)
And according to Mrs. Baker, "You've successfully created a rainforest!"