"My urban third graders, most of whom had never gardened, developed a fascination for rotten things," reports Jeanette Peaspanen from Ashtabula, OH. "Their explorations of decomposition helped them better grasp natural cycles and delight in seeing life spring from decay."
What Rots and What Does Not
Before creating an outdoor compost pile, Jeanette prompted students to explore "rot" from different angles. "I kicked off our studies by inviting students to bring old jack-o-lanterns from home to contribute to a fall compost pile," she explains. They also left one in the classroom for students to regularly observe, draw, and describe. The questions and comments flowed. One student's idea that apples would also rot prompted a discussion about whether different types of apples would rot at the same rate. Jeanette and her kids brought in five apple varieties, then staked out their ground. "Most students theorized that the softest ones (in this case, Fuji and Cortland) would rot most quickly," she explains. Their predictions were, in fact, upheld. But that didn't end the discussion. Next, the kids wondered whether sugar, which they decided made soft apples so sweet, makes things rot, and another experiment idea was hatched.
The class next brainstormed factors that they guessed--based on experience and observations--might speed up "rotting." Again using apples as the subject, these third-grade sleuths compared decomposition times of apple pieces under the following conditions: heat or cold, wet or dry, small pieces or large, with and without air or salt, and in sterile mix or regular soil. Moisture, air, and soil, they concluded gave compost the biggest boost.
After their preliminary investigations, students set out to create an outdoor pile. "I used to use a black plastic bin, but it was tough for students to turn the pile," says Jeanette. So she created a simple system using fencing wire wrapped around four metal corner stakes with hooks on top. "With this design, it's very easy to open one end and have each child fork a bit off the top, then move it to the other side," reports Jeanette. "By doing this daily, we have very quickly turned garbage to compost." Home and snack leftovers, straw, leaves, garden debris, and horse manure nourish the 3- by 3-foot pile. The students even made a trip to a local grocery store in search of fresh (high nitrogen) scraps.
When Jeanette explained to students that she had switched from the black bin to an open one, she asked whether they thought the color might affect the decomposition rate. "Some kids thought that color might affect the temperature, so we tried leaving some envelopes in the sun, then wrapped black paper around half of them," she explains. When her pupils tracked, then graphed the daily temperatures, they discovered that the black envelopes were, in fact, warmer inside. But they also discovered, via a dramatic firsthand experience, that there were other factors than color that can affect the temperature. "When we added several garbage bags of freshly-mown lawn clippings, the kids were amazed to find that the internal temperature (measured with a long compost thermometer) soon shot from 58° to 150° F!"
"This project was invaluable and easy to organize and sustain," says Jeanette. "When difficulties arose, such as unpleasant smells in the pile, I engaged students in problem solving via research or new experiments."
Just how did Jeanette know that her students had learned which types of materials are actually recyclable in this fashion? Shel Silverstein's poem, "Sarah Sylvia Cynthia Stout, Would Not Take the Garbage Out," laid the groundwork. "I asked students to list ingredients featured in the poem that Sarah actually could have composted and those that she should not have tried to compost," she explains. The class put question marks by items of which they were still uncertain, creating yet another opportunity for scientific studies.
Fill a plastic bag with once-living materials (e.g., cut fruit, moist bread) and hang the bag on the bulletin board with a sign reading, "What do you think is happening in this bag?" Encourage students to observe the bag and explain their predictions.