I'd say "Diggy Liggy Lo" and "Jambalaya" for starters. Maybe Carlton Frank's "Oh Mom"? How about "Jolie Blonde," with a big "Ayyyyy, hey hey, Ohhhhh, ha ha" for a second verse?
There's also "L'Arbre Est Dans Ses Feuilles," popularized by Zachary Richard, one of those accumulative folk songs where each verse is longer than the last -- a heart in a bird in an egg in a nest on a branch in a tree. I know hand motions that go with it (which may have originated in Quebec summer camps). A big hit with kids.
Also, there are several CDs of Cajun children's music available, such as "Fait le Hoogie-Boogie" ("Do the Hokey-Pokey") by Michael Doucet and friends.
Kids love music and love to do things. Have them participate as musicians for part of the program. Pass out rythm instruments, shakers, rythm sticks, small jingle bells in a piece of leather, small drums (oatmeal containers) and invite them to join in. Teach a sinple dance and have them dance. Have their parents join in.
Leslie
Teachem to second line, New Orleans style, wave white handkerchief in right hand, twirl minature umbrella in left hand while following on behind the other. Play Mardi Gras Mambo for proper atmosphere.