You might want to omit the repeats in the "Twinkles", but I would be more worried about them during the second Chopin Prelude...maybe play the 7th one (A major) instead?
Well, I of course thought about the second Chopin, but I might go ahead and chance it. It's strange and different enough (for most of them) that it might actually get their attention, but if it doesn't, it's only a page long and sandwitched by two fast and up-beat pieces. Plus, it's a great contrast for the other two. I will continue to consider it though.... and your suggestion is good.
I will probably take your suggestion and omit the repeats in the Twinkle.
Greetings.
I think it's great that you chose these pieces. Make sure to tell them about the variations(How they are pieces made upon a theme). I am playing them myself(still needs perfecting). I haven't yet played the preludes yet, but that's gotta be good. Any reason you chose this repertoire? 
Yeah, I thought Twinkle and the Variations would be good for several reasons... 1, they will recognize the theme 2. we could actually do some learning about the form and have some sort of communcation about the variations and recognizing the theme within it... and so on. Plus, I think they will just love it.
Well, I have chosen the Chopin's because they are short and probably impressive for those guys... plus one of my big things is to help them be more exposed to "Classical" music, and Chopin's preludes are big on my list. Also, I am going to be doing a solo concert that programs these preludes (and some others) and I am looking to get in some lower-stress performances with them. So, it seemed like a great choice to me.
The Twinkles I chose primarily because of their expected appeal to the audience... yet they can learn something new too. Plus, why not have those in my repertoire ?

I am needing to fill in the program a little more, as I am aiming at about 20-25 mins. I thought it would be fun to end with some sort of flashy jazzy piece that they might recognize, like the Entertainer or something. I am open to any suggestions. I don't think I will be doing any Disney or SpongeBob, they will recognize Twinkle, and part of the point is to help them be exposed to music they don't necessarily hear all of the time, but will probably enjoy. As a side note, a lot of those Disney pieces don't actually sound like what the kids know when only played on the piano, because normally there is singing with it. So, they might not even recognize it anyway.
One thing I thought might be fun to do, is have somebody who has never touched a piano before volunteer to come up and learn something that I would play a duet with ... but, we'll see about that

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Thanks for your responses,
m1469