"When I was a kid, my favorite book was Miss Nelson is Missing."
With its twisty tale of spitballs and secret identities, Miss Nelson is Missing is a classic of children's literature. And this sentence? It's a classic example of a declarative sentence.
"Julie taught her goldfish how to cook."
That's an impressive feat. We still can't get our cat to stop unraveling the entire toilet paper roll just for fun. We can, however, tell you that this statement of fact is a declarative sentence.
"Tommy decorated his locker with pictures of cheesecake."
Well, that's one way to make a statement. So is this declarative sentence.