Explain why the coin is able to float on top of the water in this glass.

Surface tension is the result of water molecules pulling inward with a strong attractive force. 
The attractive force brings the molecules on the surface of the water close together.
The attractive force causes the surface of the water to be drawn toward the water molecules beneath the surface. 
Since there are no water molecules above the surface, there are uneven forces. This causes surface tension, allowing the coin to float on the water’s surface.

Surface tension is the result of water molecules pulling inward with a strong attractive force. This attractive force brings the molecules on the surface of the water close together and causes the surface of the water to be drawn toward the water molecules beneath the surface. Since there are no water molecules above the surface, there are uneven forces. This causes surface tension, allowing the coin to float on the water’s surface.

While unproven, it uses facts to support part of a conclusion. it is still factual and has predictive power, however.