I'm embarrassed to admit I'm not sure here (and this is helping my fifth grade grandson). A complex sentence has two closely related ideas joined by...

I'm embarrassed to admit I'm not sure here (and this is helping my fifth grade grandson). 

A complex sentence has two closely related ideas joined by a conjunction. Draw one line under the conjunction in each sentence. Draw two lines under each of the two closely related ideas. The conjunction is easy enough but would the two closely related ideas be the complete portion of the sentence before and after the conjunction? For example:

1. John James Audubon studied drawing in France when he was a boy.

2. Then he studied birds after he moved to a farm in America.

3. Audubon ran a general store as he continued to study American birds.

Thanks for the help!