IDK if this is *the* one you are looking for, but this is the one I used last Christmas with our preschool teachers...

T'was the week before Christmas at the nursery school
And all the weary teachers were losing their cool!
Santa searched for the ones that gave their time and hearts
he wanted to thank them but how could he start?

So many hours, they worked without fuss
They worked for the children; they all gave so much.
What could he do to show them their worth;
The difference they made with all their hard work.

"I know" Santa said, "I'll open their eyes.
They'll see clearly the impact they have on small lives.
They'll see smiles on faces that their work puts there;
They'll see kindness in children taught the lesson to care."

"They'll hear laughter from families that share in their days
They'll get hugs that without them would just go away.
And at night when they rest, they'll sleep soundly and know
That their teaching hearts keep the children aglow."