I mentioned this example elsewhere in this thread, so I'll just repeat it here:
> Just today we did an activity where all the kids 'drew' a visualization of a certain math problem and then we passed the tablets around and added on top off them and then I showed the results on the projector. There was laughter, story-telling, kids helping each other, moving around the classroom, you name it.
I do group activities that involve creating things together that explore the topic. (I look at technology not as a 'subject' but as a 'language' or 'medium'.) So, at home, rather than finding an educational app for them, I would recommend giving them a tablet so they can film the things they experience. Things they see in the backyard or things they make. They can record themselves explaining a topic they learned about. Have them make music (the byte.co Music Maker app is a good one for a child who has no experience with it) and have them mess with vector-drawing or 3-D modeling apps. Then talk to them about what they made and help them get to the next level. The tablet is the 'medium' and you are the 'scaffold'. They need you to find out where to go next.
And, yeah, put the tablets away half the time so they can experience things directly. (Sounds like this is perhaps where your concern lies.)
I've also had great success with Twine once they can read.
Thanks for the great question! I hope this helps. It's really cool that you asked.