Welcome to Chordie!
Wow, a group of children? Group lessons are a challenge at any age, but it might help to know the age group we are dealing with?
Many Popular tunes will have at least three Chords.... and not all of them easy for young fingers to deal well with. You could start out with the abbreviated "cheater" chord fingerings at first just to get the music going on so at least the kids are focused, but you will want to stress the more proper chord fingerings so that those that are able to get them right off have a sound foundation to build upon.
Please check out the Public Books and other resources available here on Chordie for "easy beginner" music selections. You might find a few hiding in there that you could print off and use. Also consider using the transposition feature to help find chordings that might be easier to manage albeit in a different key.
Welcome Aboard and Hope you find the site and Community helpful to you in whatever way we can be. There's a great group of folks here that I'm sure will go out of their way to assist you in promoting guitar as a means of musical expression among your students.
Thanks for Joining &
Take Care;
Doug
"what is this quintessence of dust?" - Shakespeare