Each group needs:

• breadboard ($3.50, available in electronic stores or online, for example http://www.pololu.com/catalog/product/351)
• battery holder ($1.50, available in electronic stores or online, for example http://www.pololu.com/catalog/product/1159)
• 4 AA batteries
• terminal block ($0.50, available in electronic stores or online, for example http://www.pololu.com/catalog/product/830)
• VOC sensor ($18, for example, sensor model TGS 2620 at http://www.figarosensor.com/)
• multimeter (~$10)
• 1/8 of a kitchen sponge for each VOC source
• Elementary and Middle VOC Worksheet or High School VOC Worksheet, one per student (depending on grade level)

To share with the entire class:

• 1 wire kit ($1.30, available in electronic stores or online, for example http://www.pololu.com/catalog/product/313)
• VOC sources (gather items from the classroom, such as cleaning products, white-out, permanent markers, dry erase markers, non-toxic markers, school glue, non-toxic glue, whiteboard cleaner, and duct tape; ask students to bring in items from home, such as nail polish, nail polish remover, alcohol, scented cosmetics/shampoo, vanilla extract, perfume, spray deodorant, cleaning products such as dish soap, air freshener, paint cans, and moth balls)
• 2-3 buckets (or any containers that can hold about a quart of water)
• 1 light-emitting diode (LED)