I usually teach helping verbs through a song (it also has linking verbs). My kids usually love it and we often sing it while transitioning.
It is sung to the tune of "The Stars and Stripes Forever"
am, is, are, was, were, be, being, been (clap, clap)
have, has, had, do, does, did, shall, would, should, could
may, might, must, can, will, that's the end (clap, clap)
and we will/won't sing it over again...
(they usually look up at me on the last line whether or not we'll sing it again).
I hope that helps!