I just got my very first smartphone. First app I bought was DragonBox. I've heard lots of good things about it, and I think I played around with a free online version a while back (although it doesn't seem to exist now).
It is fun to play with, even though I know my algebra. I still need to test it with kids who haven't learned algebra yet, to see how much sense it makes to them, and how well it transfers to paper-and-pen(cil) algebra.
I did find a few bugs, and I hope the makers will set up some sort of program to get users to report bugs, so they can fix them.
Bug #1 (minor):
Here's the screen. I wanted to subtract a/5 from both sides, but that's not possible. I had to multiply both sides by 5, subtract a, and then divide both sides by 5.
Bug #2 (minor):
I was penalized for changing c+c to 2c. Not sure why.
Bug #3 (bigger):
I divided both sides by x, and got x = 1/3. Dreambox said that was right. But that leaves out the other possible answer, which is x = 0. Yikes! I think dividing by x needs to be a wrong step in the game.
I bought the version for age 5 and up ($5.99) by mistake. I'm looking forward to checking out the version for age 12 and up ($9.99), too.
Even with bugs, this game is great. I'm impressed.