And here I thought, and was getting excited that, it was going to be a phone with a physical keyboard. It's not. It's just a keyboard you can attach to your phone with a magnet.
Edit: I was wrong. It is a phone. I'm excited again!
Most ready to solder tin sold has a flux core. Meaning you don't really need flux, that is, if you do it the way the original commenter did said.
Another thing that can help is a soldering iron that doesn't take 15 minutes to heat up. If it takes 15 minutes to heat up, there is no way it can transfer enough heat for more than a few pins, as the iron will cool down too much to get a decent joint.
Writing by hand is a good way to get fine eye hand coordination. I think, at least for younger kids, writing should be primary during development. Around 12 years of age it could be phased towards computers instead.
My bad. I'm excited again.