Explain that a petroleum-based poison called hexamine is also one of the ingredients of this product. Hold up three mothballs in a glass jar. Explain that this moth-killing chemical called napthalene is another mystery ingredient. Hold up the jar containing molasses or maple syrup. Tell students this represents an ingredient that can cause cancer in animals and humans.
Students simulate tar affecting the cilia.
Ask students to guess how much tar passes through the lungs of a smoker who smokes two packs a day for a year. Have students line up along a wall. Have the first student take a book off the stack and pass it to the next student, who passes it to the next, etc., fire-brigade style. The first student is to continue taking one book at a time from the stack and passing it along, while the student at the end of the line creates a new stack of books. Explain to students that they represent cilia and the books represent harmful dust and germs.