Start. Go with the flow. Stop.
My 9-year-old picked up Duolingo last year and got into the flow of it.
The streaks appealed to her. She started doing daily lessons. And it was great to see her motivation to learn grow. Over time she also picked up some other languages too.
She got to a 328 days streak. At one point she was excited to get into the VIP 365 club, I can't remember the official name for it.
However, over time she kept doing the work, but I could see she wasn't enjoying it so much. She kept showing up for the streak, rather than for truly wanting to learn.
It had become a chore and actual a stressful point for her. She would go to bed and then get up a few minutes later panicking that she hadn't done her Duolingo.
Then one day she turned around to me and said "Can I stop doing Duolingo?". I said "of course, you've done so well with it. More than I've ever done!"
She had a sad and stressed look on her face. I asked her why she wanted to stop and she said she was stressed about it and just didn't want to do it anymore. Then on the spot she deleted the app, we hi-fived and hugged.
I'm proud of her for sticking with it for so long and picking up a whole variety of language phrases. But most importantly, I'm proud she recognised how it made her feel and made a decision to stop.
Whilst this may seem like 'no big deal' in the perspective of life, I personally think these things can lead to many stresses as we are forced to continue to do things that lack meaning or damage us in little ways.
To help me make decisions, I often try to put myself in their shoes and ask myself how I would feel. I apply the same standards to myself as I do to my kids. It's pretty simple and straightforward, but it seems society has forgotten that children are real people too.
Give the children the ability to stop. Even if they can't explain why, there's usually a good reason.