Tuesday, October 19, 2010

Pumpkin, pumpkin, what comes next?

It's that time of year. Pumpkin patches and corn mazes are thriving. Families and even classrooms of students are picking pumpkins and decorating and carving them. But have your students thought about what comes next? After the pumpkin is carved?

This is a perfect opportunity to teach your students about the science of decomposition. Decomposition is one of the most importance processes in the garden and in nature. It's the process by which fungus, bacteria and invertebrates chance matter that was once alive (as in fallen leaves, rotting logs, and yes, even pumpkins) into fertile soil. It's not just a necessary part of the process in the garden; it's a crucial part of the life cycle. The following experiment will provide a wonderful opportunity to experience and observe this immeasurable important ecological function first hand.

The details of decomposition will become more familiar to children as they get older. The important concept for young children to walk away with is that the dead material helps grow new life. As they watch the pumpkins in this experiment rot, they will see beetles, worms, mold and other tiny organisms participating in this cycle. But there will also be millions of organisms too small to be seen participating in this process.

What you will need:

  • 2 pumpkins (1 carved and 1 not carved)
  • hand lenses
  • Optional supplies: Sign explaining your experiment, your camera and the books Pumpkin Pumpkin by Jean Titherington and The Story of a Garden by George Levensen

You will need to find a protected spot near your classroom or home where you can leave your pumpkins to decompose on a patch of soil or under a bush. If you're conducting this experiment at a school instead of your home, it's a good idea to talk to the grounds staff about your experiment and you may want to put up a sign to prevent your experiment from getting "cleaned up."

  1. Ask the children what they think will happen if the pumpkins are left outside. Record their ideas and place the pumpkins in their outside spot. Take a picture if possible to track the process. Ask them to describe what the pumpkins look like now and record their answers.
  2. Visit the pumpkins every day or at least twice a week. During that time, you can read pumpkin stories out load, starting with Pumpkin Pumpkin and later, near the end of your experiment, Pumpkin Circle. Each time you visit, ask the children to describe the appearance of the pumpkins and what is happening. Record their observations with pictures and/or words. Take another picture. 
  3. Using hand lenses, have students search for worms, beetles and other decomposers at work and discuss their role in "munching up the pumpkins" and helping them turn back into soil. Be sure to have the children look for mold and fungus as well.
  4. When the pumpkins are gone (or mostly gone), continue to visit the spot to see if new plants begin to grow there.
  5. Review the predictions the class made about what might happen to the pumpkins. Display your photographs and read the children's observations about the pumpkins over time. Ask what happened to the pumpkins, Why? What helped the pumpkins break down? What would happen if they didn't break down like this?
Decomposition is a concept that's easy to reiterate on a frequent basis, especially in the garden. What might happen to a tomato left on the ground? Who might want to each my apple core? There are many possibilities to keep in mind and remind students of the life cycles taking place in nature and in the garden.

Looking for more pumpkin fun? Here are some ideas for going even deeper!
  • Place another object, like a pile of wet leaves, another fruit or vegetable or a piece of plastic or styrofoam next to the pumpkin to compare what happens to it. Which decomposes more quickly? Which has more bugs and decomposers on it? Watch and learn together!
  • Place 4 to 8 pumpkins a few feet apart and have students hope over each one. It's pumpkin leap frog!
  • Try a pumpkin slalom, where children run in an s-shape through a line of pumpkins.
  • Have a pumpkin seed tasting. Roast seeds from a carved pumpkin or buy them in the store. Taste and compare seeds prepared in a variety of ways: roasted, toasted, salted, unsalted, etc.

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