Go to Kelly's space and scroll down the right hand side until you arrive at the links under The geek in me.

She has a good selection of science links here. You might find some too easy and some just right. Will you find any too hard? Choose a place that is different from your sisters and tell them whether you would recommend it.

Of course I'm going to recommend the interactive rock cycle!

(And to better answer that question, Why does skin form on heated milk? explore WiseGeek.)