The Cider Shed Field Notes
During apple harvest, Talia's class studied an old stone path beside the cider shed. The path sloped toward a low garden bed. The students marked places they could observe safely and recorded what they saw after several days of changing weather. They did not touch the loose stones or enter the shed.
After two heavy rains, the class found a narrow groove in the soil along the lower edge of the path. Small soil clumps were in the garden bed below the groove. The class also saw that several loose pebbles had moved downhill. No pebbles were found uphill from their original marks.
Near the shed wall, a thin sandstone slab had a crack. In October, the crack was 2 millimeters wide. After six freeze-and-thaw cycles in December, the crack was 5 millimeters wide, and two small chips were beside the slab. The students used a ruler and took a photograph each time; they did not break the slab.
A dry north wind blew across a bare patch near the path. The class placed a tray 30 centimeters south of the patch and found 18 grams of dry soil in it after the afternoon. A second tray placed 30 centimeters north held 2 grams. The wind was blowing from north to south during the observation.
A plant root grew through a crack in a stone border around the garden bed. In spring, the crack was 3 millimeters wide. In late fall, it was 7 millimeters wide. The stone border and the root were photographed from the same place each time. The class then made simple models to compare agents.
For each model, students used the same kind of loose soil, the same tray size, and 120 grams of starting soil. They changed one condition at a time. In the water model, 40 milliliters of water flowed down each sloped tray. The bare-soil tray lost 22 grams; the tray covered with straw lost 9 grams. In the wind model, a fan blew across dry soil. The tray with a low screen lost 6 grams; the tray without a screen lost 19 grams. The measurements were made after one test for each model.
The class drew a word model for one possible change: water or wind acts on loose soil, soil particles move to a new place, and the moved particles may collect where the force is weaker. They drew a different model for a crack: water enters a rock crack, freezes and expands, and the crack can become wider after repeated cycles. These models were predictions to compare with observations, not pictures of hidden events.