Chords, Continued

Last week, I introduced this 8-yr-old to the delights of squished diminished chords.  Today we took it a bit further.

Me: You play the fa, and I'll play the ti and re.  [We play these all together].  Now, how does that sound?
Girl [grinning, with a look of delight]: Scary!!
Me: You know, if we just add one more note, it can sound really different.  This time, I'm still going to play the ti and re.  You still play the fa, but can you play the so - the open D - at the same time?
Girl [with 'are you sure about this?' written all over her face]: Okay...
Me [once we've played, and her face registers delight all over again]: So? How does that sound?
Girl [still grinning]: Really happy!!

We then played that chord (dominant 7th) followed by its resolution, G major.  She was rather excited that it sounded so finished.