Investigating Decomposition Processes of a Plant

This activity is designed to help students to make careful observations of the decomposition of a pumpkin. They will learn to take notes on their observations and allow these observations to lead to questions that we can make investigable. Some key vocabulary will be "observation, note-taking, questioning, decomposition (or breaking down), and mold."

This activity is intended for Kindergarten, but could be adapted to nearly any grade level. This idea lends itself easily to the "Pumpkin Unit" many teachers conduct in October. This is an ongoing experiment that could be referred to throughout the year in reference to trash/recycling, life cycle/structure of a plant, as well as an example of careful note-taking and observation. Teacher will need an aquarium or terrarium, covering of some sort (such as tinfoil and duct tape), and a windowsill (optional). Teacher will designate (or create) a small notebook for each student to use as his/her "Pumpkin Log" (maybe it could even be in the shape of a pumpkin).

This activity is an extension of the pumpkin unit we do in the fall. We take a field trip to a pumpkin patch, and each child chooses a pumpkin to take home. The teacher is allowed a few "extra" pumpkins for classroom use. One pumpkin we carve into a "Jack-o-Lantern." Each child experiences that pumpkin with each of the five senses (they even touch the stringy insides of the pumpkin). We talk about how the pumpkins are used as decoration and as food. The teacher makes a pumpkin dessert to share with the class, and bakes some seeds for them to eat. This activity would extend that unit through the school year. Not all the seeds are baked, and a few should be planted to go next to the terrarium on the windowsill (preferably in a clear container so we can see the roots).
After the Jack-o-Lantern has served its purpose, place it in the terrarium. Put some litter (e.g.: wrappers, empty soda can, anything non-biodegradable), dirt, and some of the stringy insides from the pumpkin in the terrarium as well. Make the dirt moist with some water. Cover the terrarium with some plastic wrap, tinfoil, and whatever else will work to create an air seal, and duct tape it on. (Decomposition smells unpleasant, and we don't want an unpleasant smelling classroom). Place the terrarium on the windowsill somewhere accessible enough for the students to look closely at it without the chance it will be knocked off the sill or the cover torn. Place the pot with the seeds planted in it to grow next to the terrarium if possible. Approximately once per week, each student should have the opportunity to closely observe the pumpkin in the terrarium and record those observations in his/her pumpkin log. The teacher will need to model observation and note-taking many times before the students will have enough practice to do this on their own.
Once students seem to have a handle on observation and note-taking, the next step would be to look back in their notes for questions they thought of while observing the pumpkin. Were any of those later answered with the passage of time? Are they something we could investigate? For those questions we cannot investigate, is there part of it we can, or a way to change the question to make it investigable?
By the end of the school year, the terrarium should be holding essentially dirt and litter (as the pumpkin will have fully - or nearly fully - decomposed). This can lead to a discussion about "where all the pumpkin 'stuff' went" and why the litter is still essentially unchanged. This discussion, of course, segues beautifully into a unit about garbage and recycling. Also, by now the seeds next to the terrarium are a plant. This demonstrates the full life cycle, and helps explain composting.

One way to manage the weekly observations is to have each table group have a day where part of their morning activity is pumpkin observation. For example, on Monday, the "Triangle Table" (of six children) observes. On Tuesday, the "Rectangle Table" will observe, and so on.
This activity is an extension of the unit we have done in the past. We've never watched the decomposition process in the classroom before.

The teacher will periodically collect the pumpkin logs to review them. The quality of observation and note-taking will be obvious in those. Also, the classroom discussions around the decomposing pumpkin, growing seeds and unchanged trash will give the teacher an indication of the level of inquiry the students are at in the classroom.

Strand
I. History and Nature of Science
Sub-strand
B. Scientific Inquiry
Standard
The student will raise questions about the natural world.
Benchmark
1. The student will observe and describe common objects using simple tools.