Why is there “at” here?

It’s incorrect and probably a mistake.

I think it's a typo. The 'at' feels odd, at least to me.

It could be a dialect thing, but it just reads as wrong to me. At isn't really used like that, in my experience. It's probably just an error, but someone will correct me if I'm wrong.

That seems like a typo.

Typo?

It’s could be dialectal to southern american which I have experience with. If it is, then it would be something along the lines of “he’s chewing at a wad” which means to work away at the wad and the “on” would be to emphasize that the chewing is a continuous action.

Short story: An editorial correction was only partially made/was partially missed. This feels like someone accidentally typed "chewing at", likely from their own dialect, and accepted the editor's change to make it say the correct words ("chew on") without accepting the change to delete the original entry ("chew at").

The phrase “___ing on” is a way of emphasizing that somebody is intentionally doing something continuously or repeatedly for an extended period of time. I think it also often implies that the person is continuing to do this action despite conditions that might make them choose to do something different. Example 1: Jack is a great wrestler, but he’s getting older and a lot of people think he can’t win championships anymore. I think that’s nonsense; he needs to keep wrestling on! Example 2: I tried to tell Emily that she should be quiet, since we’re in the library, but she keeps whistling on. “Chewing at” is definitely uncommon, but it’s almost always interchangeable with “chewing (on).” So by saying that the coach is “chewing on at” a piece of gum, this sentence emphasizes that the coach is chewing his gum for a somewhat long period of time, despite a reason (talking to his players) that might make him stop. This is definitely an informal way of saying that, though, and as you can tell, it is quite likely to be interpreted over text as a mistake.

This reads as dialectal to me. It’s using at in the same way that one would “chip away at” something. But this is not standard English and I would disregard it. If anything the at is a small intensifier, putting more emphasis on the chewing.

In some varieties of English, “chew on” is considered a single unit verb with a subtly distinct meaning from just “chew” by itself. In the case of “chewing on at a wad of gum,” my guess is that “chewing on” implies a continuous or habitual action regular to this Coach character.

It's a typo. You'd say either chewing or chewing on (or much more rarely chewing at, usually if it's something that takes a LOT of chewing, like a doorframe for example). Never 'on at'

Its a typo.

I don't see a problem with this though it's not a common way to say this. The "on" is an aspectual particle (preposition) and adds a continuous/progressive meaning to the verb and "at the gum" specifies what is being chewed

To my ear, it suggests that the wad is getting worked on: “he’s chewing away at a wad” would present a similar image to me, but we're talking about awfully subtle differences here.

It's a mistake.

No one would say "... Chewing on at a wad of gum." "Chewing on a wad of gum" is correct. "Chewing at a wad of gum" is technically incorrect, but could be used in certain dialects (like here in Rural Canada) to imply that they're working hard at it. Though often that is said: "chewing /away/ at". "My kids been chewing away at that Hubba Bubba you got him all day! His jaw is gonna be sore tomorrow" You could also say, in an informal sentence, "hacking (away) at some trees and shrubs" "working (away) at his screenplay" etc. But rarely/never would you say "chewing on at..." or "working on at..."

I think maybe it means in context that he's continually chewing the gum. As others have said it may be a typo and is definitely odd

It's a typo. This kind of typo usually happens when someone cuts and pastes and then changes something or goes back and adds a word without proofreading afterwards.

This could be correct if its used as a shorter way of saying smt like "chewing on and on at a wad of gum". This would be used in a similar way to "he races on at the local track", meaning that he continues to race at the local track. This would mean the sentence is trying to convey that he's continuing to chew on his gum, merely subbing in the "at" for the second "on" to avoid repetition. It looks wrong at first but if you think about it, it's technically grammatically correct, just a combination of weird things makes it seem like a typo. I hope this explanation makes some lick of sense. I'm a native speaker and this puzzled even me for a bit.

It's a mistake

It shouldn't be there, you're right.

As others have said, maybe a typo, but to me it's giving a dialect difference. I'm just not sure which though. Maybe when they say "chewing on at a wad of gum" they mean "on" as in he is continuously chewing the gum and not talking? I'm not too sure to be honest

Typo. Should be "chewing **on a** wad of gum"

I think it's a typo.

It’s pretty uncommon, but doesn’t seem to be a typo. I think it’s more likely that it’s the phrase “chewing on” (continuing to chew) and the word “at.” So “chewing on at a wad of gum” = “continuing to chew at a wad of gum.” I don’t know if it’s technically wrong or not but I definitely don’t think it’s a typo.

Chewing at would mean that the child is not chewing the wad yet but starting to chew before it is in the baby's mouth. Like chomping at the thing. I think that's a mistake. I assume they wanted to have a "chewing on/at ..." but the / wasn't allowed.

Something that you'll hear spoken more often than written. It's grammatically incorrect but some people might use two prepositions to emphasize that the chewing has some anger to it. Coach isn't just chewing on a wad of gum. He's chewing on *and* chewing *at* a wad of gum. The prepositions are combined to make it shorter while still giving emphasis. Edit: People are 100% wrong that it's a mistake but they are probably right to say it's a dialect thing. This is a construction I've heard (and probably said) in the southern US.

Native speaker here... 100% that is a typo

either a typo word, or it should be on/at. as in chewing at or chewing on a wad. either would work in non-perfect english, but not together.

Error.

This looks like an error at the level of text entry.

Incorrect

It wouldn’t necessarily be wrong to say “he is chewing AT a wad of gum,” and it definitely isn’t wrong to say “he is chewing on a wad of gum.” It is wrong to say “he is chewing at on a wad of gum.”

Typo

It’s wrong.

It could very well be a typo as others jave said. It could also be a very colloquial phrase - "chewing at a wad" in this context could be correct, depending on the dialect of English (it seems more southern or rural), in which case "chewing on" could be similar to "continuing to chew". Overall I would disregard it as a construction for now. Hope this helps