An idea that I think would be great to show the students is to test what would happen if you did a closed system. Along with the closed systems that we made for our lab, I think it would be interesting to make a closed system of just water and one of just the land. For younger students they may need the visual that both systems need to work together to make a successful living environment. If I had older students I think it would be interesting to allow them more freedom in what goes into their ecosystems. In high school we did this project, but we got to put whatever we wanted in the ecosystem. This was a positive experience because it allowed choice and made the learning more meaningful, but it was also a negative experience because the ecosystems didn’t thrive like they may have if it were more balanced from the beginning.
In the future I think this would be a great lab to use in an elementary classroom. I think that the students would really stay engaged. Making observations would be beneficial to the students and they would really get to see a lot of change. The discussions that would come from the observations would also be great for the class. The students would get first hand experience, and if there are a lot of different bottles in the class they will hopefully get a good range of observations. I don’t know how long I would use the bottles in the classroom, but I think the longer they get to observe the changes the better. I guess it would just depend on how successful the lab went.
The majority of the time we had a lot of success in our ecosystem. The plants flourished, the snails reproduced, there was condensation, and flies turned up somehow in the top part of our bottle. The last week we decided to test what no sunlight would do to our bottle. The bottle changed drastically over the course of one week. The plants took a turn for the worse, all of the organisms died, the water got cloudy, and the elodea turned brown. The flies seemed to die as well. It became clear to us that sunlight is the ultimate energy source in our bottle and that the lack of sunlight ultimately changed every element of our ecosystem. There was also a great deal of mold on our soil, presumably caused by excess moisture created by the lack of evaporation. While the ecosystem has changed drastically due to this change, it has not “died” as the mold is a living element. If we left the system in the dark, we predict it would have become overtaken by the mold.
If we changed this experiment, firstly we would consider planting different seeds. The bean sprout grew fast, but its growth was restricted by the height of the bottle. If we used exclusively broccoli or pepper seeds, perhaps the ecosystem would flourish more. We also would consider making the ecosystem taller by adding another bottle on top. We also think we could put the bottle in various outdoor areas, as they were indoors and at a controlled temperature. Another change would be to compare and contrast two separate ecosystems, one with the elodea, snails, and daphnia and one with just seeds, soil, and uninterrupted water. We would also consider the size of the ecosystem and perhaps compare/contrast ecosystems of varying sizes (ie 1 L bottles vs 2 L vs 1 Gallon bottles.) There are many ways to utilize this experiment and to adapt the experience to many units of curriculum.