Does anyone know the definition for controlling ideas?

plz i need it for homework and i cant find it i will give 10 points to the person who gets it right PLZDoes anyone know the definition for controlling ideas?
A ';controlling'; idea is an idea that makes a reader ask a question. Any time a topic sentence has a good ';controlling'; idea, the reader will have his or her curiosity raised.





In effect, the reader will say (in the mind) questions such as How? or In what way? or What does that mean?





Examples of good ';controlling'; idea topic sentences:





It is difficult to read English for someone who has used Farsi. (Why is it difficult? How is it difficult?)





Yesterday, I had an unusual experience on the bus. (What experience did you have? Why was it unusual?)





Example of a topic sentence with NO ';controlling'; idea:





Last year, my wife and I went to visit Banff, Alberta. (A fact, but I have no questions to ask you; if you had said, ';had fun in Banff,'; then I would have questions for you!