So my 11 year old just started working! I chose farming though I regret it cuz she's 99.9% useless there. How can I teach her more things?

Patience, grasshopper. All things in good time.

I agree that the kids are useless as farmers. I'm somewhat obsessive-compulsive about the layout of my garden, and I never ask my adoptee to help. The other skills are somewhat useful, but as an example,

But does choosing them to help farm kill that chance of them catching things? Or helping keeping grass and weeds in order?

I have a bit of a problem with this myself. After I tell my adoptee to help clean up the town, sometimes they just continue to follow me like I didn't even tell them to clean up the town, and most of the time, there is still trash/weeds around. Sometimes, my adoptee will pick up one piece of trash/pull a weed, and either stand there doing nothing or return to me and keep following me when the cleaning is still not done! Only occasionally will my adoptee clean until all the trash is gone. Is this a glitch?

Other than teaching the kids, I just keep em away from me. They are just frustrating, get in the way and never help. Lol!

Lol, I do the same, JenniMM! My kid gets on my nerves following me around all the time. Sometimes he gets in the way when I'm trying to catch a bug and I end up missing it. So usually when I first open the game, the first thing I do is tell him to go play so I can get him out of the way. He's never done anything to help anyway.

I agree that they're worse than useless when trying to farm. If my mayor has a task like the thistles or knotweed I'll sometimes ask the adoptee to help clean up the town; if s/he has to catch things like the killer bees or slugs perhaps I'll get the adoptee swinging a net. In both circumstances they will perhaps get only one or two items at a maximum, though, so YMMV on whether it's worth the extra bother.

All of this sounds a lot like my real life kids.

Ok. I guess that means my troubles with adoptees are just natural.

Lol! So true!

Anyway: My kid keeps following me around like I never asked her to do anything. She's almost 17!! What happens when she's full grown?

When she finish 16, you will retire and she will be the new mayor.
But she will never be 17, she will skip to 18 when you retire (Or maybe 19)

I think you have to have them "learn" the various tasks, because once they are grown up, they take over the Mayor's duties. They are a pain especially when planting as they are always in the way!!

Telling them to go play or go away or even go inside works... sometimes.

Here's my trick if your bestie is following around too closely and getting in the way: