Why does the author end with the sentence 'Drier summers mean less fog, and less fog means a thirstier forest'?
Read an Informational Passage · ELPAC Grades 3–5 reading. The correct answer, and the reasoning behind it.
A longer factual text, with questions about the main idea, supporting details and vocabulary.
Read the passage. Then answer the questions.
Drinking the Fog
Coast redwoods are the tallest trees in the world. Some grow more than 300 feet high. A tree that tall has a problem. Water is heavy, and pulling it from the roots all the way to the top takes a great deal of work.
Along the northern California coast, thick fog rolls in from the ocean on summer mornings. The fog drifts through the redwood branches and collects on the needles. Drops form, join together, and fall to the forest floor like light rain. Scientists have measured this. In some forests, fog drip supplies as much as a third of the water the trees receive in a year.
The trees also drink from above. Redwood needles can take in water straight from the fog, so the top of the tree does not have to wait for water sent up from the roots.
The fog helps other living things too. Ferns, banana slugs and young redwood seedlings all depend on the damp ground the fog leaves behind. Drier summers mean less fog, and less fog means a thirstier forest.
The question
Choose the best answer.
Why does the author end with the sentence 'Drier summers mean less fog, and less fog means a thirstier forest'?
- To explain that redwoods do not need much water.
- To describe what banana slugs eat.
- To show that the forest is in trouble when there is less fog.Correct answer
- To prove that the scientists measured the fog correctly.
Why “To show that the forest is in trouble when there is less fog.” is correct
This asks about the author's purpose, which means reasoning past what the sentence says to why it is there. The passage has already established that fog supplies much of the forest's water, so the closing sentence follows that idea to its consequence. Ask the child what the sentence warns about rather than what it states.
Why the other answers are wrong
- To explain that redwoods do not need much water. — The passage argues the reverse, opening with how much work a tall redwood does to move water.
- To describe what banana slugs eat. — Banana slugs are named as creatures that need damp ground; their diet is never discussed.
- To prove that the scientists measured the fog correctly. — The measuring is mentioned earlier in the passage, and the final sentence is about consequences, not evidence.
Practice more of this
More reading practice for Grades 3–5, or see the ELPAC practice test for grades 3–5. For other grades, see free ELPAC practice tests by grade.
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