What is the main idea of the passage?

A lighthouse illustrates a public good because many ships can share its beam and excluding users is difficult. (The passage develops the two relevant features and then separates them from the mistaken idea of zero cost.)

Why can charging each ship be difficult?

Nearby ships may see the beam whether or not they paid for it. (The second paragraph says excluding non-payers from an already shining beam may be difficult.)

What does “excluding” mean here?

preventing someone from using or receiving something (The context concerns keeping non-payers from receiving the visible signal.)

What cost does the passage name?

equipment (The final paragraph lists workers, equipment, and energy as real lighthouse costs.)

The Lighthouse Everyone Can Use: Level 1 Reading Comprehension Questions

A lighthouse sends a warning beam across dark water. When one ship uses that light to avoid rocks, the beam remains available to another ship. One captain's benefit does not use up the signal.

It can also be difficult to show the beam only to ships that paid for it. Once the light shines, many vessels nearby can see it. Economists use features like these to describe a public good. One person's use does not greatly reduce use by others. Excluding non-payers may also be difficult.

The term does not mean the lighthouse is free to build or maintain. Workers, equipment, and energy still have costs. The example instead explains why collecting payment from each user can be hard and why communities may support a shared service together.

Comprehension questions