Make them learn Tom Lehrer’s “The Elements”.
Maybe don’t make them learn Tom Lehrer’s “Be Prepared” or “Smut”.
Definitely, Sama Kama Wacky Brown
Almost anything by Allan Sherman.
“Old MacDonald Had A Farm”, done the right way: Each child sings a stanza, repeating all the animals (in order!) from the previous stanza and adding another one of his choice, so the stanzas get longer and longer. So after a while, a stanza starts of look like this:
Old MacDonald Had a Farm,
E-I-E-I-O!
And on his farm he had some… (try not to have to stop to think here!)
DOGS!
E-I-E-I-O!
With a woof woof here and a woof woof there,
Here a woof, there a woof, everywhere a woof woof,
Baa baa here and a baa baa there,
Here a baa, there a baa, everywhere a baa baa,
Neigh neigh here and a neigh neigh there,
Here a neigh, there a neigh, everywhere a neigh neigh,
Oink oink here and an oink oink there,
Here an oink, there an oink, everywhere an oink oink,
Honk honk here and a honk honk there,
Here a honk, there a honk, everywhere a honk honk,
Quack quack here and a quack quack there,
Here a quack, there a quack, everywhere a quack quack,
Moo moo here and a moo moo there,
Here a moo, there a moo, everywhere a moo moo
Old MacDonald had a farm.
E-I-E-I-O!
Next child sings:
Old MacDonald Had a Farm,
E-I-E-I-O!
And on his farm he had some… ummm… ummmmm…
BIRDS!
E-I-E-I-O!
With a chirp chirp here and a chirp chirp there,
Here a chirp, there a chirp, everywhere a chirp chirp,
Woof woof here and a woof woof there,
Here a woof, there a woof, everywhere a woof woof,
ummmm,… ummmmmm…
Baa baa here and a baa baa there,
Here a baa, there a baa, everywhere a baa baa,
ummmm… uh, ummm…
Oink oink here and an oink oink there,
[EVERYBODY: YOU LEFT OUT THE NEIGH NEIGH!!!]
Here an oink, there an oink, everywhere an oink oink,
Honk honk here and a honk honk there,
Here a honk, there a honk, everywhere a honk honk,
Quack quack here and a quack quack there,
Here a quack, there a quack, everywhere a quack quack,
Moo moo here and a moo moo there,
Here a moo, there a moo, everywhere a moo moo
Old MacDonald had a farm.
E-I-E-I-O!