To share with the entire class:

• seven 2-liter plastic bottles; ask students to bring from home or rinse bottles from recycling bins; one bottle must have its screw-on cap; have a few spares in case they are needed for any experiments
• portable drill with 1/16-in and 3/16-in drill bits (preferred), or hammer with nails, to put holes in the bottle cap
• scissors, to cut the plastic bottles
• 1 liter of one type of pervious material, such as tire crumbs, course-grain sand, 3/8-in granite or small pebbles; use what can be recycled or scavenged for free
• impervious surface material, such as a piece of aluminum foil, a foil pan, a plastic lid, a paver stone with a model-size house and car, or a concrete cast you have created; use what can be recycled or scavenged for free
• ¼-in clear acrylic tubing, 3 feet; estimated cost of $10
• construction paper, one sheet per student
• drawing implements, such as pencils, colored pencils or markers
• 2 measuring cups, each able to measure up to 2 liters
• access to water and a sink