I know this is late, but here is your answer for anyone else that may be looking
The topic sentence includes the main idea.
The summary is about one-third the length of the original.
The summary is clear and concise.
Hope this helped
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Step-by-step explanation:
The main idea is about bats and how scientists were studying them to see how they can fly so well without hitting things.
The summary is 71 words, opposed to the 221 word original. One third of 221 is 73
The summary doesn't include many words that may be hard for people to understand, nor does it have an redundant statements