Question

6 which sentence from the article best represents the central idea?
a to test his theory, dr. fish teamed up with engineers from duke university and the u.s. naval academy.
b the secret seems to lie in the way tubercles break up the flow of air and water, creating tiny vortices, or swirls.
c because the attachments decrease drag and delay stall, these turbines keep turning even at low wind speeds.
d dr. fish loves the idea of using nature’s designs to invent new technologies.

7 read the sentences from paragraph 13:
one problem for turbines is that wind is not constant. even in gusty places like north dakota and kansas, strong winds do not blow all the time.
what is the meaning of constant as it is used above?
a steady
b visible
c common
d valuable

(handwritten: \main idea\ over \central idea\, \go there, but understand the paragraphs before and after\ near question 7. bottom: \grade 5\, \houghton mifflin harcourt publishing company. all rights reserved.\)

Explanation:

Question 6

To find the central idea, we analyze each option:

• Option A: Describes a test of a theory, a detail, not the main idea.
• Option B: Explains a scientific detail about tubercles, not the overarching idea.
• Option C: Details turbine functionality, a supporting detail.
• Option D: Captures the core concept of using nature's designs for new technologies, which likely is the central idea.

We analyze the context: "wind is not constant" and "strong winds do not blow all the time". This means wind isn't steady.

• Option A: "steady" matches the idea of consistent wind (opposite of not blowing all the time).
• Option B: "visible" is about sight, not wind consistency.
• Option C: "common" refers to frequency of occurrence, but the context is about wind's consistency, not how often it occurs.
• Option D: "valuable" is about worth, irrelevant here.

Answer:

D. Dr. Fish loves the idea of using nature’s designs to invent new technologies.

Question 7