Soils
Lesson 2
Where Do Dead Plants Go?
Students create compost bags made with and without redworms and monitor those bags over time to explore the connection between organic matter and soil, which they began in Lesson 1. They will observe the formation of humus, one of the main components in soil.
3. Lesson set up and Management
SYSTEMS 1.1-Properties: Understand how properties are used to identify, describe, and categorize substances, materials, and objects and how characteristics are used to categorize living things
GLE 1.1.1 Understand simple properties of common natural and manufactured materials and objects: Sort common materials and objects using a simple property and Identify and describe the differences between common natural and manufactured materials and objects using properties.
GLE 1.1.5 Understand physical properties of Earth materials: Sort rocks based on size, shape, and other physical properties and Explain how some Earth materials are used by living things.
GLE 1.1.6 Understand characteristics of living organisms: Identify observable characteristics of living organisms and Observe and describe characteristics of living organisms.
SYSTEMS 1.3-Changes: Understand how interactions within and among systems cause changes in matter and energy
GLE 1.3.8 Know that most living things need food, water, and air.
GLE 1.3.10 Know that plants and animals need a place to live.
• Soil may contain animals, plants, and their remains
• Over time, dead plants become part of soil
• Composting, especially with worms, is an effective way to recycle old plants and other discarded organic matter
3. Lesson set up and Management
Materials:
Dampen the garden soil ahead of time in the re-sealable plastic bag or in a bucket or tub. This reduces splashy messes at student desks. It should not be mud - just slightly moistened.
An alternative to pairs of students putting their worms in re-sealable plastic bags is to use plastic disposable "left-overs" containers.
Keep a jug of aged water on hand as students will need to put some in compost bags occasionally and will use it later to water seeds. “Aged” water is water that has been allowed to sit in the jug with the cap off for at least 24 hours to allow dissolved chlorine to evaporate out of the water.
If there is a good undisturbed spot in the classroom, leave two 9 oz cups of aged, settled water and several eyedroppers available for students over the next several weeks. This way they can have access to water over the next 5 weeks to add a few drops to the compost bag as needed.
Student Management:
Caution students to handle the worms gently and not too much so the worms survive the encounter.
Caution students not to squeeze the bags.
Student punching holes in the bag. |
Punch holes in the upper part of the bag. In fact, Figure 2-1 in the teacher's manual is misleading. If students punch holes as shown in the picture, the holes will be too low. Punch 2 or 3 sets of holes within an inch of the seal. The worms really head for the holes if the holes are anywhere near the soil line.
Sometimes soil gets compacted into the bag. If this happens, gently put a hand under the bottom of the bag and jostle it a bit. This will loosen up the soil to make it easier for worms to move through and more observable for students. Caution students not to squeeze the bag!
A good way to keep worms in the dark is to give each set of partners a lunch sack to put their compost bag in. They can even decorate them ahead of time for a jazzy "worm condo". This has the added benefit of being easy to store. They can be hung with thumbtacks on a bulletin board and thus are up and out of the way. When students need to observe composting activity and progress they simply take the compost bag out of the lunch sack, observe, and then return it to the lunch sack and bulletin board. If you don't feel this is dark enough, line the lunch sack with a sheet of black construction paper.
Student observing worms with a hand lens.
Writing Support:
It is useful to set up a record sheet that more closely resembles the format of an investigation. This format elicits the same responses from students as Record Sheet 2-A and gives some practice for writing an investigation. See Alternative Record Sheet 2-A here.
Reading Support:
There are several good non-fiction and fictional books about worms and composting. Among them are Worm by Jill Bailey, Diary of a Worm by Doreen Cronin, Wonderful Worms by Linda Glaser, An Earthworm's Life by John Himmelman, Earthworms, Underground Farmers by Patricia Lauber, Compost Critters by Bianca Lavies, Earthworms by Claire Llewellyn and Wiggling Worms at Work by Wendy Pfeffer. These books give insight into the anatomy and life cycle of worms, and the way worms help to make soil.