The other reason is the extent of teachers' own knowledge about language.
"Within the extent of your knowledge," Francisco said quietly, "you are right."
Well, if those songs are the extent of your knowledge, you'd better have legs to make a man fall on his face.
'We will examine the extent of our knowledge,' he said.
In 8th grade French you are being taught to the full extent of the teacher's knowledge.
These documents constitute the extent of our knowledge about Imperial's life.
But at least now he knew the extent of the Chinese's knowledge.
That's the extent of their knowledge of society between men and women.
Since these were things he must have known already, the motive had to be learning the extent of her knowledge.
I had him wondering about the extent of my knowledge.