After an inventory of lab supplies, the team began a series of investigations and experiments to help them better understand plant systems. Celery soaked in salt water overnight dramatically demonstrated how plants absorb water. The team bravely tasted celery slices to see how far the salt water traveled up the stalk. Conclusion: "Not so delicious. If it had been polluted water that could affect the plants and food crops." Setting up the erosion experiement with inclined trays of plain soil (no vegetation), sod (short roots) and plants (longer spreading roots) to determine how various root structures help prevent hillside soil erosion.
For the Rain Garden project, the team's next objective was to understand how different soil compositions affect natural filtration. They concocted their own "polluted" water by mixing dirt, debris, and water. This solution was poured into containers with layers of sand only; sand and soil; sand, soil, and gravel. Conclusion: the sand only had the fasest drainage but the container with 3 different layers filtered the "pollution" the most effectively. Then it was off to get field samples from the proposed Rain Garden site.
Soil core samples were taken from the site of the proposed Rain Garden site. The students wanted to test for pH levels as well as see how nutrient levels change with depth. The team's mentor, Mr. Van Winkle coached them in mapping the locations of the holes from which soil samples were obtained. The samples were carefully labeled 'A" and "B" for each hole to denote the sample's depth.
Field studies replaced field trips as the campus became an outdoor laboratory. Additional soil samples were taken from around the school. Working together, the team set up supplies, conferred with Mrs. Nordskog on correct procedures, prepped and recorded field notes for each sample. The samples were used for multiple tests.
Top: The third-graders set up a demonstration to show how rain water infiltrates and is absorbed into the soil. The bottom of the container simulated the water table. Once the sand and gravel layers were completely saturated, the water level rose to form an above ground "pond" in the depression. (The students commented on how the "rain" from the watering can was eroding the sandy "hill" to expose the gravel layer. It was great to watch them make these type of connections on their own!) This is helped the students understand why the Santa Clara river is dry most of the year but can be quite full with surface water in a rainy season. It also showed how the rain garden would function. The level of the "pond" was marked on the container was put outside to see how long it would take for it to evaporate leaving a dry river bed again. Below- The students set up to test the soil samples taken from the area near the proposed rain garden site. They analyzed pH, nitrogen, phosphorus, and potash levels. It was important to know our soil components when selecting plants for the rain garden. Working afterschool and on Saturday mornings, we were fortunate to have help from parents like Mrs. Kelley.