How to Make a Replica of an Atom Using a Toilet Paper Roll

Make four, evenly spaced pin-sized holes in an upright toilet paper roll.

Feed one strand of thread through two opposing holes with the help of a needle. Cut the needle off the thread, leaving three inches sticking out of each hole.

Ball up the ends of the thread with your fingers and a little spit, using up about one inch of thread. Place tape around the knot you've made to keep it secured.

Feed a thread through the other two holes, balling up the ends and taping the knots. Each hole should have about two inches of knotted threat sticking out of it.

Tape the threads together where they intersect inside the toilet paper roll.

Pull gently on one of the strings. When you pull one thread out, all the other threads are pulled inside the tube, leaving the knots against the toilet paper roll.

Ask your students to make inferences about the toilet paper roll, including what they believe the inside might look like and the reason for the strings behaving as they do. Use this example as a lead in to discuss how scientists determined the structure of an atom without ever seeing inside one.