Second graders headed out to the school gardens, imagining they were aliens from another planet on a mission to find out what soil is made of, so they could start growing food on their planet.
In the Garden Classroom they dug soil samples and identified some components they could see. Students wondered what might be in soil that we cannot see, and observed that soil is a mixture of dead and living things.
They compared soil samples from two different sites (a garden bed and a bare slope under trees), and discovered that soil varies in color, texture, and composition from place to place. To help separate out the components, the soil samples were put in a jar with water and brought into the classroom to settle into visible layers: humus will float at the top, and rock/sand particles will sink to the bottom.
Students investigated compost at different stages of decomposition, and learned how dead plants return nutrients to the soil to help other plants grow. They observed worms and centipedes and other decomposers that help with breaking down the compost.
In the vegetable garden they pulled up and composted the winter cover crops to get the garden ready for spring and they also planted peas. Peas, and other legumes, have the special ability to take nitrogen from the air and turn it into nitrogen in the soil that the plants can use to help them grow. In the presence of a certain bacteria in the soil, they grow nodules on their roots in which they make their own fertilizer. So in a couple months, we’ll have tasty peas, and healthier soil!
These hands-on investigations provide memorable connections to support students’ science learning. Thank you to the volunteers who helped make the activities possible: Doug Brenhouse, Xinqi Gong, Gail Barry, Candace Webb, Katie Sbay, Kim Foster, and Harriet Wong.