There are over 10,000 species of moss. Mosses are amongst the oldest plants to be successful on land. Mosses are classified as bryophytes, a group of nonvascular plants without internal tissues for circulating liquids. Instead of using roots to absorb nutrients, as many plants do, mosses absorb water and nutrients from their outer surfaces.

In this activity, to learn about the biological needs of mosses, students will grow and maintain their own moss terrarium. Through daily maintenance and observation, students will identify those factors necessary for the successful cultivation of moss.

Grade Level: 6 – 8th Grade
Subject Matter: Life Sciences
National Standards: NS.5-8.1, NS.5-8.3

Ready to Cut Out Grass?

Summertime doesn’t have to mean hours behind the lawn mower, at least for shade-dwellers. David Benner, horticulturist and moss enthusiast, cut grass out of his life 40 years ago. In its place, he cultivated moss. He now has 25 different species of moss growing on his property near New Hope, PA. Benner, whose son Al Benner runs Moss Acres, shares tips for moss cultivation.

Activity Materials
Digital cameras – one for each student or group of students
Terrariums (transparent plastic or glass containers) – one for each student or group of students
Small plastic magnifying glasses – one per student or group of students
One bag of topsoil – available from nurseries or plant suppliers
One bag of pebbles – also available from nurseries or plant supply stores You will need enough pebbles and topsoil cover the bottom of each terrarium.
Water – two to three cups per terrarium
Small spray bottles – one per student or group of students
Moss specimens – these can be collected outdoors or bought from a florist or horticulture supply store
Alternative: Terrarium Moss Kit – order from www.mossacres.com. You may want to use one of these kits as a model for students.

Vocabulary
Moss: a type of nonvascular plant with short stems that usually inhabits moist shady areas.
Nonvascular plant: a plant that lacks fluid-carrying vessels for transporting nutrients.
Rhizoids: thread-like anchoring structures found on mosses.
Spores: small, usually one-celled reproductive structures produced by seedless plants.
Substrate: the surface on which an organism grows or is attached.

What To Do

1. Start the lesson by having the students watch the Science Friday Video, “Ready to Cut Out Grass? Try Moss.” Ask students if they have noticed any mosses growing in their local neighborhood and what they look like. Review the information given in the Science Friday Video on where mosses are found and how they absorb nutrients.

2. Have students search for mosses in their local neighborhood and take pictures of the various locations and types of mosses they find. Mosses can be found in sidewalk cracks, driveways, under trees or on tree branches or bark, or in local parks, especially in rocky areas. Instruct students to record observations such as the location where the moss was found, moss color and appearance.

3. In the classroom, review their pictures and observations. Discuss with students any similarities and differences found. What conditions do mosses favor? What conditions do they think are needed to cultivate moss?

4. Hand out moss specimens to students and have them use the magnifying lenses to observe the parts of the moss. How are mosses different than other plants? Where are the rhizoids located and what is their function? Tell students that they will be growing and observing their mosses for the next few weeks.

5. Have students place pebbles along the bottom of their terrarium to form a layer about an inch deep. On top of the pebbles, pour a layer of soil about three inches deep. Why do students think that there is a layer of pebbles underneath the soil?

6. Have students place their moss on top of the soil, ensuring that the rhizoids are in contact with the soil by patting down on the moss.

7. Have students pour about two to three cups of water on top of the moss, ensuring that the water fills a pool or reservoir within the layer of pebbles. Why is soil and water necessary if moss acquires its nutrients from the air?

8. Fill a spray bottle with water. Gently spray the top of the moss with water until the moss becomes moist.

9. Have students place their terrarium in a secure area that receives indirect sunlight. Why is the terrarium not placed in an area that receives direct sunlight?

10. Over the next few weeks, have students observe and record any changes in the growth of the moss. Students should track how many times a day they water the moss and how much direct or indirect light the moss receives. Does the moss grow quickly or slowly? Does it spread to other parts of the terrarium and if so how does it reproduce? Under what conditions does the moss demonstrate optimal growth? What variables may have caused the moss to grow differently or not at all?

What’s Happening?
Mosses are simple non-flowering plants that thrive in moist shady environments. They are believed to have evolved millions of years ago from the first plants that were able to survive on land and out of water. Mosses lack true roots. Instead, they have small filaments called rhizoids that they use to anchor themselves to surfaces. Instead of using roots to absorb water and nutrients, mosses absorb them from the air. Mosses reproduce through spore germination, and require thin films of water or moisture for spores to travel.

Although mosses can be found in many environments, they require specific conditions in order to thrive. Successful cultivation of moss will depend on how well these conditions are simulated and maintained. Even though mosses absorb water from the air, a moss that is fully or partially enclosed in a terrarium or placed indoors might need additional watering in order to thrive and reproduce.

Topics for Classroom Discussion
• How are algae and mosses different?
• What would happen if a different substrate other than soil (sand, mulch, etc.) were used?
• What would happen if other plants were added to the terrarium?

Extended Activities and Links
Have students observe detailed imagery of their moss under a microscope, and have them draw a colored diagram labeling the various parts of the moss.

Have students research and explain how mosses are ecologically important (soil erosion prevention, soil builders, mineral cycling, etc) for the environment and other beneficial uses of moss to humans other than landscaping (packing materials, peat, fuel, filters).

Investigate whether mosses really do grow on the north side of trees:
http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p043.shtml

View images of various types of mosses:
http://bryophytes.plant.siu.edu/mossimage.html

Explore general information on bryophytes:
http://www.anbg.gov.au/bryophyte/what-is-bryophyte.html

How long does moss take to grow from spores?
http://blogs.evergreen.edu/researchambassador/projects-2/moss-in-prisons/

This lesson plan was created by the New York Hall of Science in collaboration with Science Friday as part of Teachers Talking Science, an online resource for teachers, homeschoolers, and parents to produce free materials based on very popular SciFri Videos to help in the classroom or around the kitchen table.

The New York Hall of Science is a science museum located in the New York City borough of Queens. NYSCI is New York City's only hands-on science and technology center, with more than 400 hands-on exhibits explore biology, chemistry, and physics.