While sometimes you will be asked to make an inference about what you have read, other times you will be asked to find information that is explicitly stated in the passage. The details in the writing can also help you to characterize the passage as a whole. Characterizing the passage may involve determining a general theme or central idea, or may be more specific, such as summarizing the content in the passage.
The following is a sample passage from the ACT Reading Test, followed by a Central Ideas question.
This question requires the reader to find information that is directly stated in the passage. Looking through the passage, we can see that PET is discussed in the second paragraph.
This paragraph states that PET allows the neurobiologist to observe activity in the brainstem and the sensory, visual, and frontal cortices of the brain. This paragraph therefore supports answer choice A.
Answers to questions that involve Central Ideas, Themes, and Summaries will be directly stated in the passage. This question concerns the last paragraph of the passage, specifically about when the formation of synapses occurs most rapidly.
While the entire last paragraph talks about the formation of synapses, the end of the paragraph describes the formation of synapses in the prefrontal cortex. It is described as forming “at such a rate that it consumes twice as much energy as an adult brain” and at a “furious pace.” This implies that the prefrontal cortex is where the synapses form most rapidly. The paragraph states that the development of the prefrontal cortex occurs from the second half of the first year through the first decade of life, or from about 6 months to 10 years old. Therefore, the answer is G.