For the teacher:

• 1 gallon bottle
• 1 bag potting soil

Each group needs:

• 2-liter bottle with base cut off and no cap
• 2" x 2" piece nylon stocking or cheesecloth
• rubber band
• 4 oz cup course sand
• 4 oz cup aquarium gravel
• small coffee filter
• large bowl, approximately 2"– 3" deep
• empty 12 oz cup, to be later filled with dirty water