The passage says the old conclusion about beavers 'turned out to rest on thin evidence.' What does thin…
Read an Informational Passage · ELPAC Grades 6–8 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.
The Beaver Comes Back
For most of the twentieth century, California treated the beaver as a nuisance. Trappers had already removed nearly all of them by 1850, and the animals that remained were often relocated or destroyed, because their dams flooded roads and pastures. By the 1940s many wildlife managers had concluded that beavers had never really belonged in much of the state.
That conclusion turned out to rest on thin evidence. Researchers working through fur-trade ledgers, mission records and old newspaper accounts found beavers described in rivers from the Oregon border to the edge of the Mojave. The animals had not been absent. They had been removed so early that nobody alive remembered them.
The distinction matters, because a beaver dam is not simply an obstruction. Water that slows behind a dam sinks into the ground instead of racing downstream, which raises the water table and keeps side channels wet into late summer. Those channels give young salmon cool places to grow, and the moisture they hold can slow a fire moving across a valley floor. After two recent Northern California wildfires, researchers found green vegetation standing around beaver ponds while the surrounding hillsides had burned.
None of this makes beavers easy to live with. A dam built in the wrong culvert still floods a road, and the consequence lands on a county budget rather than on a river. What has changed is the first response. California now runs a restoration program for the species, and a landowner facing a flooded field can request a flow device, a pipe set through the dam that lowers the pond without removing the animals that built it.
The question
Choose the best answer.
The passage says the old conclusion about beavers 'turned out to rest on thin evidence.' What does thin evidence mean here?
- Evidence too weak to support the conclusion built on itCorrect answer
- Evidence collected only from narrow rivers
- Evidence that researchers found difficult to read
- Evidence that has since been lost
Why “Evidence too weak to support the conclusion built on it” is correct
This tests an everyday adjective used in an academic sense, which is a frequent source of trouble for English learners who know only the physical meaning of 'thin'. The metaphor is carried by the verb 'rest on': if a conclusion rests on something, that something has to bear weight, and thin support cannot. The paragraph then proves the point by describing the records researchers found, so the surrounding text confirms the reading.
Why the other answers are wrong
- Evidence collected only from narrow rivers — This applies the physical meaning of 'thin' to the rivers, which the sentence is not describing.
- Evidence that researchers found difficult to read — Old ledgers and newspapers might well be hard to read, but the passage says researchers worked through them successfully.
- Evidence that has since been lost — The records were found rather than lost, which is precisely how the old conclusion was overturned.
Practice more of this
More reading practice for Grades 6–8, or see the ELPAC practice test for grades 6–8. For other grades, see free ELPAC practice tests by grade.
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