doing class reading, need recommendations

[stbjohn2]

Glutton for punishment that I am (I get very nervous speaking in 
front of more than 2 people at a time) I have agreed to be a guest 
reader for Read Across America Day at my son's school. I would like 
to read something from one of the HP books, and am wondering if 
anyone has suggestions on what would be a good selection (or if 
someone else has done this and what they used.)

Specifically, it's supposed to be about 15 minutes worth of reading, 
and I am reading to 3rd graders. I'm thinking I want something 
somewhat self-contained, not the big, climax scenes where I'd have to 
explain tons of stuff that's already happened. I haven't really 
started looking thru the books, but my first thoughts are perhaps a 
visit to Diagon Alley (either first or 3rd book), or perhaps Harry's 
visit to the Burrow (book 2).  Something with Fred and George would 
definitely be fun.
(I actually think The Unexpected Task from GoF is hilarious and would 
be great fun to read aloud, but 3rd graders are a little young to see 
the humor in Harry looking for a date....)
Thanks to anyone who has some thoughts to share
Sandy