Setting iPad / laptop to stop working after a certain period of time?

[seriouslylong]

So I'm getting my dd an iPad for Xmas as she really wants one but it's difficult to get her off technology.

One of her friends mentioned her iPad will not work after an hour and a half and I'm wondering how to put a timer like this on the iPad?

She also has a laptop and I would like to put a timer on that too but she does need it for homework - so if anyone has an idea on how to go about this please help

If you already know she's going to be a nightmare is she really ready for one?

You can just use the timer on the clock, and set the alert to 'stop playing' 😀

DH has programmed the modem to disconnect DS devices after certain time. He has no internet until the next morning.
There were tantrums to start with but now he just plans his gaming around it and it works fine. It spares the incessant "but mum, I just need to do one more thing...." conversations. He's also learnt not to start anything he can't finish.