You will need a transparent hurricane glass or another deep glass. It is important to have a deep glass such as a hurricane glass so the children can see the paper clips floating or sinking in the water. A hurricane glass provides a wide circumference for the many objects you will be placing in the glass. You also will need water, paper clips, paper towels and liquid soap.
Fill the hurricane glass with water, leaving about two inches at the top of the glass. Drop the two paper clips in the water. Observe what happens. Tear or cut a section of paper towel that is a little bigger than the paper clips. Drop the paper towel section into the water. Place another paper clip on top of the paper towel section. Repeat this so that you have two paper towel sections with two paper clips on top. Observe what happens. Finally, drop a little liquid soap into the water. Observe what happens.
When you drop the paper clips into the water, they sink. When you drop the paper clip on the section of paper towel, the paper clips float toward one another and the section of paper towel sinks. Finally, when you add liquid soap to the water, the paper clip will sink.
In a hurricane glass full of water, the water particles composing the water are attracted to one another much like magnets are attracted to one another. The particles stick together. However, if there aren't any water particles in a certain direction -- such as above in object -- then the particles stick to one another below the object or to the right or left of the object. This rule creates surface tension. Surface tension is why two paper clips will stick together on the surface of the water. Therefore, when you place the paper towel section on the water, you place the paper clips in the water without breaking through the surface tension. The drops of soap work in the opposite way, breaking the surface tension.