Coin Through Latex

Objectives

• Explain the importance of observation when doing science.

Materials

• Per Demo:
  latex (dental dams or clear latex balloon with end cut off)
  coin
  cup
  elastic band

Key Questions

• Did the coin really fall through the plastic?
• What do you think happened?
• Touch the latex rubber. What do you observe about how it feels?
• Can you figure out how the trick works?

What To Do

Preparation:
Do the following preparation out of students’ view.

1. Stick a coin to the underside of a piece of latex by pushing it through the centre. It will stretch the latex and appear to be sitting on top of the latex, although it is housed inside.
2. Stretch the latex over the cup, so that it appears as though the coin sitting is on “top”, and fasten it with an elastic band. The coin will actually be on the under-side of the latex.

Instructions:

1. Have a volunteer push the coin “through” the latex, and watch your students’ surprise as it falls into the cup!
2. Have the students try to guess how the coin passed through the latex.
3. Give them hints and let them try and solve the illusion by playing with the materials themselves.
4. Lead students to the explanation that sometimes you can take a thing and stretch it so it looks like it’s nothing at all. If latex rubber is stretched, it can become virtually invisible. It’s still quite sticky though, and can hold a coin in place on its underside.

Other Resources

Teach Tuesday | Coin through Rubber