Choose a clear container for the terrarium so students can clearly see what happens inside. Glass canisters, water jugs, large mayonnaise or pickle jars, fish bowls and large plastic salad bowls work well. Students also commonly build terrariums from 2-liter soda bottles.
Place a 1 inch layer of small stones in the bottom of the container. The spaces between the stones will help with water drainage.
Place ½ inch activated charcoal on top of the stones. The charcoal acts as a filter and cleans the water.
Put the sphagnum moss directly on top of the charcoal. Do not dig into the charcoal. The moss acts as a barrier between potting soil and the charcoal.
Place 2 inches of potting soil on top of the moss.
Dig small holes in the soil, one per plant. Bury the roots of the plants in these holes.
Add decorative objects. This step is optional.
Mist the terrarium soil and the inside container walls with water. Do not saturate the soil, but mist until the soil is moist to the touch.
Seal the container with the lid or cover.
Place the terrarium in a bright area where it will receive indirect sunlight.