• several triple-beam balances (or electronic balances), accurate to at least 0.1 g
• 2 one-pint plastic bags with zipper closures per student
• several permanent markers for labeling the plastic bags
• 8-20 pounds, more or less depending on class size and student plans for experiments, of good quality potting soil (the most expensive you can afford)
• several garden trowels, large spoons and/or plastic cups for digging and scooping soil
• 10-12 large carrots, cut into pieces about 3-4 cm long and 2-3 cm in diameter
• inexpensive watercolor paintbrushes, one or two per group, for brushing dirt from the carrots prior to weighing

Depending on what questions the student groups decide to test, you may also need:

• other types of soil (for example, soils with high clay or sand contents, topsoil from a nearby woods, garden or inconspicuous lawn area, etc.)
• refrigerator space
• incubator space (Create a makeshift incubator from a large cardboard box, such as one that computer components are shipped in, lined with aluminum foil. As the heat source, use a very small desk lamp or a 25-watt light bulb screwed into a base obtained for a few dollars at a hardware store. For safety reasons, only use the incubator during school hours, unplugging it overnight or running it on a timer. Monitor the temperature and try to maintain it at about 40 °C or 100 °F; if it gets too hot, open the box flaps slightly; if it is too cool, use a higher voltage light bulb.)
• several thermometers
• several small beakers, graduated cylinders and bowls for mixing soil or adding measured amounts of water or other substances
• safe, acidic liquid such as lemon juice or vinegar