What is the main idea of the passage?

Attraction among water molecules creates surface tension, making a liquid surface behave somewhat like a stretched skin. (The passage explains the unequal surface forces, names surface tension, and applies it without treating the skin as literal.)

Why are surface molecules pulled inward?

They have fewer water neighbors above them than beside and below them. (The second paragraph connects the missing neighbors above with an unequal inward pull.)

What does “resist” mean here?

oppose or push against (Surface tension makes the top oppose stretching rather than give way without force.)

Which animal is supported by surface tension?

a water strider (The final paragraph names a light water strider as an example.)

The Skin on a Drop of Water: Level 1 Reading Comprehension Questions

Fill a cup carefully, and the water may rise slightly above the rim before spilling. The curved top looks as if it wears a thin skin. No separate film covers it. The effect comes from attraction among water molecules.

Inside the water, a molecule is pulled by neighbors in many directions. At the surface, there are fewer water molecules above. The unequal pull draws surface molecules inward, making the surface resist being stretched. This behavior is called surface tension.

Surface tension can support a light water strider when its legs spread the force without breaking the surface. It also helps small drops become rounded. The “skin” can still break when enough force is applied. The image is useful, but the surface remains liquid water held together by molecular attraction.

Comprehension questions