My 10yo daughter got a school-provided tablet. This would have set off an avalanche of time-wasting grooming virtual horses, tending virtual gardens, raising virtual horses and doing $deity-knows-what, were it not for the fact that she is limited to an average of 1 hour of screen time a day. She already had a phone which runs a home-built (Android) distribution with a few tweaks to keep her sane. It runs a variety of free software, does not show any advertising, and has a white-listed time limit on activities.
As the mentioned tablet is made by this site's favourite company and, as such, rather restricted in what can be done with it, I started to create a few tools to get her to use the thing in a more productive (versus the mentioned 'consumptive') way. For now, this is mostly related to reading books [1][2] and other documents from our rather extensive personal collection. I also got her a Raspberry Pi 'just for fun, to see what can be done with it'. We'll probably set it up to control the RGB LED spot she got for her birthday, 'just for fun'. I put this between quotes because I do have a deeper meaning with these experiments: show her that she can use her creativity and imagination to make things happen that did not happen before. Things she made herself, which her friends do not have. That creating something can be more giving than grooming that virtual horse for the umpteenth time...
My other daughter is 3, she goes to daycare ('dagis' in Swedish) for 15 hours per week. At 'dagis' they also have one of those mentioned tablets, when I ask her what she's done that day she'll respond with 'I played on the tablet'. But did you not do anything else? 'No, I only played on the tablet'. This does not seem to be true, as they state children only get about 10 minutes on the thing, but it does make me doubt the wisdom of having these tablets in a daycare centre. The whole idea with sending her there is that she can interact with other children after all...
[1] https://apps.owncloud.com/content/show.php?content=167127
[2] https://apps.owncloud.com/content/show.php?content=168132