(Entry 2) Game flow and the user experience.

I've never really thought about game flow, until this week. Miss Bit, my 7 year old, has an edutainment game system, a Leap frog Didji. I insisted we get it for her, to help her along with her school work in an interactive manner.
I snagged the unit when I took her on the bus, and watched her play. She dug into Sonic the Hedgehog , sending him dashing after golden rings to earn points.
*sigh*
The audible sigh came from her as the game switched over to the spelling portion of it. I watched as she continued to play. She would enter a focused concentration during the actual gaming portion, then get jolted out as soon as the spelling words came on.
We'd had a problem recently with another game with her skipping over the questions and just playing and now I can see why. Perhaps an edutainment device isn't the best ideal, if it doesn't serve both purposes well. The education portion should be fun, and as engaging to play as the game itself, if not integrated into the game itself. If the game disturbs the flow of play, then is it a good game at all?

This has me wondering further about the kinds of fun you build into a children's game. How do you ensure the game is challenging, but engaging. Easy enough to enthrall and include a sense of accomplishment, but hard enough to keep you playing. Even further what should the life span of a game be? With an edutainment game do you want the game to grow old so it needs replacement? Or do you sell upgrades to increase enjoyment? Perhaps thats a deeper question. How do you produce a game that not only hits the "fun" and "flow" but also generates the income you need?