An enclosed ecosystem is an ecosystem that has no outside gasses, liquids, nor anything (other than sunlight) go in, or out, of it.
a 2-liter bottle
an 8-once bottle
Step 1: Prepare the Bottles
Empty and clean the bottles. Take the labels off.
Step 2: Measure
Take the smaller bottle and measure the size of it on the larger bottle.
Step 3: Cut
On the circle you just measured, cut a hole.
Step 4: Get Some Soil
Go outside and dig up 2-3 cups of soil and get some plants. Put it in the small bottle. Put the worms in the soil.
Step 5: Poke Holes and Pace
Poke holes in the small bottle's bottom. Place it in the hole to make sure it fits.
Step 6: Fill Big Bottle
Fill big bottle with water that has been sitting out for 24 hours 3/4 of the way up. put fish and plants in.
Step 7: Make a Stand
Take three paper plates. Roll two up and tape tight. Attach to the sides of big bottle, and tape. Tape the last plate on to the bottom. Place small bottle in the big bottle.
Step 8: Observe
Observe your ecosystem. Mine didn't get enough sunlight so it died in 5 days. Make sure it gets enough light.