I suggest the children/pupils should learn a song.

It is WRONG for you to PERFORM as a substitute.

Songs for students to learn are simple and teach language verb tense.

Perhaps, one of the most common taught/sung is:
My hat it has three corners
Three corners has my hat
If it had not three corners
It would not be my hat

You NEED to focus on the objective/purpose/outcome of the brief time. Students need to depart (45 minutes later)... with a new skill...they never had, before they entered the doorway.

Sincerely,
Gargoyle

Substitute teaching, secondary, (12-17) is probably one of the most difficult gigs in the entire world.

I had a "Felix the Kat" magic bag.
Five days of student engagement ... for:

No lesson plan
No paper
No pencil

Primary was standing at the door when students entered and hearing names. Names of "spark-plugs" in the class are always in conversations, as they enter.

Get on the "preferred list" ... reject others.