Middle School Classroom Chronicle

Having brought our Human Body Systems unit to its finale with functioning models of the cardiovascular system and some pretty awesome dissections, the Seventh Grade is now deep into Ecology. 

We have made the unit very place-based in our local watershed. For example, as an early activity in the unit, students simply staked out a spot for themselves to sit near one of the inlets to Lake Merritt and got still, then allowed themselves to notice the action going around themselves at a micro level, with ants dutifully carrying materials, and battles playing out between multiple mold species on rotting bits of wood. We saw a turtle doing its thing in the stream and carefully observed how each of its features represents an adaptation to its environment. As a means of exploring the cycles of matter and the flow of energy in nature, students created their own ecosystems inside tightly sealed 2 L bottles filled with water from Sausal Creek, along with Elodea plants, bladder snails, and some stream rocks and silt. Amazingly, almost all of those mini ecosystems are still thriving, weeks after having been set up, with no matter entering or leaving the systems at all. Interestingly, students also learned that bladder snails don’t need a partner to reproduce, as they saw clutches of snail eggs among the water plants in their ecosystems with only one parent snail, and they watched them hatch into youngsters.  

Students have learned experientially how each species in a community is interdependent with the others through a yarn web, where we took note of organisms at different trophic levels and noticed how the removal of a species had cascading effects on the others. In an experiment on soil generation from natural decay processes, students buried banana peels in soils that ranged from moist to dry, some of which included worms or other bugs that showed up in the soil samples they gathered. Amazingly, when we went to observe the banana peels after 3 weeks and to find their change in mass through decomposition, they were completely gone in the moist soils and largely intact in our driest, sandiest soil samples. 

Students made firsthand observations and conducted online research about plant, animal, and fungus species that grow in and around Lake Merritt, and they gave presentations to their classmates on the species of their choice, after becoming an expert in that species’ range, adaptations, and ecological health. 

Each student then researched and depicted their own complex food web based on the species living in and around Lake Merritt. Those depictions (along with their accompanying hilarious narrative stories about animal adventures) were quite beautiful and informative, showing the interdependencies among things like phytoplankton, zooplankton, herring, snowy egrets, and even the occasional harbor seal that makes its way into Lake Merritt.

Our most recent lab (featured in the attached photos) has centered on the ecology of the plants growing near the Lake, and in particular, how variations in temperature, light intensity, and soil moisture affect the plant species growing in different areas. Specifically, students laid out 1m x 1m square areas known as quadrats at each of four sites where these abiotic conditions differed, and they documented all of the specific species and the abundance of each species found at each site. We then used lab equipment to quantify light levels, temperature, and soil moisture levels at each of the 4 sites. Students are currently exploring correlations between the abiotic conditions of each site and the adaptations and abundance of the species that live there.

We will be closing out the year with an exploration of cells & DNA. We will have the chance to reflect on everything we have learned throughout the year through our newly developing lens of cells & DNA, to get an even deeper sense of life’s connectedness.