How is Dill from To Kill a Mockingbird awkward/geeky and chatty?

Dill is just a little boy. I wouldn't describe him as awkward or geeky, although he was a talker, curious, and quick to extend a challenge. 

As he told us the old tale his blue eyes would lighten and darken; his laugh was sudden and happy; he habitually pulled at a cowlick in the center of his forehead.

My teacher asked to prove Dill as awkward/geeky and chatty yet you gave me no proofs. 

As I already explained, I don't see Dill in the same way. You might be able to use the following quote for geeky.....

He played the character parts formerly thrust upon me— the ape in Tarzan, Mr. Crabtree in The Rover Boys, Mr. Damon in Tom Swift. Thus we came to know Dill as a pocket Merlin, whose head teemed with eccentric plans, strange longings, and quaint fancies.

You might consider the following quote evidence for Dill's being described as chatty..... I see it as curiosity.

The more we told Dill about the Radleys, the more he wanted to know, the longer he would stand hugging the light-pole on the corner, the more he would wonder.

“Wonder what he does in there,” he would murmur. “Looks like he’d just stick his head out the door.”

The only time Dill seems to be, or should I say act or feel awkward is when the subject of his father comes up. 

“Well how’d you feel if you’d been shut up for a hundred years with nothin‘ but cats to eat? I bet he’s got a beard down to here-” “Like your daddy’s?”

“He ain’t got a beard, he-” Dill stopped, as if trying to remember.

“Uh huh, caughtcha,” I said. “You said ‘fore you were off the train good your daddy had a black beard-”

“If it’s all the same to you he shaved it off last summer! Yeah, an‘ I’ve got the letter to prove it—he sent me two dollars, too!”