Good songs to teach a ten-year-old?

What are some good songs to teach my ten-year-old niece who wants to learn the uke? Please suggest classics like "On Top of Spaghetti" and also pop songs - I have not listened to pop since the advent of punk in the late 70's / early 80's. I've listened to punk, metal and country since then, along with folk and eclectic stuff, but the pop world is an unknown to me. Pop songs should be clean enough for an uncle to teach to a niece.

Find him simple versions of the songs he knows and likes. Just Google ukulele chords lyrics, and the song title. Often you can find simpler versions on beginners sites. Many songs originally written with 12 chords can be played with 3 or 4. Good luck. Here's a site for him to play along with when you aren't available:

http://www.ukuleleplayalong.nl/#

Search youtube for "ukulele cover". Look for the videos from young kids. There are lots of them, many from girls. Those will likely be songs your niece knows. Most are pretty clean. Things like Call Me Maybe.
Some of the kids are pretty good and their enthusiasm is infectious.

I would add:
This Land is Your Land
The Lion Sleeps Tonight
This Little Light of Mine
You Are My Sunshine
When the Saints Go Marching In

I think part of it is going to depend on what kind of music the kid has been exposed to. I like Igor's list, but i think a lot of kids who only listen to contemporary commercial pop might think a lot of great classic folk or traditional songs are corny.

On the other hand, my boy (11 y.o.) has recently taken an interest in the uke, and we're working on Scarborough Fair (picking melody) and Saint James Infirmary (strumming chords). But he's a weird kid (in the most awesome way!) who favors pre-war jazz, old Johnny Cash records, and stuff that was originally released on 78's - and couldn't be happier if all of Justin Beaver and One Dimension's recordings spontaneously vanished from the face of the earth.

Pondoro, do you think a book like this would meet your needs? It has simple arrangements (with tabs and chords) of some pretty familiar songs, though nothing very recent.
http://www.halleonard.com/product/viewproduct.do?itemid=695905&lid=2&keywords=ukulele

This is the great place to start not only for 10 years old...http://www.baby-patch.com/guitar.html

Twist and shout is the first song I ever learned and is incredibly easy! Maybe you could teach your niece that!

Whatever she likes and whatever you like. Also, be willing to try songs you aren't familiar with. There are several hits on Google where you can find two or three chord songs, if you want to keep it simple in the beginning.

I guarantee that at ten she's already got very decided opinions about what makes good music. Teach her to play the stuff she listens to on the radio or TV - fortunately almost all pop music is pretty simple three- or four-chord stuff.

John