Line the bottom of the aquarium tank with gravel.
Place the plants upright in the gravel and heap additional gravel around the base to secure them and encourage growth.
Add water to the tank, leaving approximately one inch of space between the top of the water and the top of the tank.
Place fish in the tank according to directions provided from the pet store. It is advisable to begin with a male and female of one species to establish a control against which the effects of adding more fish can be measured quantitatively.
Cover the aquarium with the supplied tank cover and place in a well-lit area.
Feed the fish in accordance with fish food instructions. Observe and record various measurements of the ecosystem for two weeks, including water temperature, plant growth in height and food consumption by fish.
Create a hypothesis about a change to the ecosystem, such as adding plants or fish, changing the type of food supplied to the fish, or using color filters to alter the sunlight penetrating the aquarium, and the effects you think it will have on the ecosystem and its members.
Introduce the change presented in your hypothesis to the ecosystem. Observe and record various measurements of the ecosystem for two weeks, including water temperature, plant growth in height and food consumption by fish.
Compare the data of the control ecosystem to the changes in the ecosystem as a result of your experiment. Report the conclusion supported by the data and whether it supported your hypothesis. Create charts or graphs based on the results and present your findings.