Correct sentence: Eagles build big nests on cliffs to raise their chicks.
Why this is correct (easy words):
- Only the first letter of the sentence needs a big letter: "Eagles" (not all caps).
- Put a period at the end to finish the sentence.
- The words are in the right order and make a clear idea: eagles make nests, the nests are big, they are on cliffs, and the nests are for their chicks.
Another simple way to say it: Eagles make large nests on cliffs for their chicks.