[veronika.ke]

Yikes, 50 kids. Bless your heart.
Here are a few things I've done with 8-year olds, I think they might transfer to a younger age too, maybe.
Countdown. My kids used textbooks, but whatever you want them to do (form a circle, find a pair, etc), start counting down. The kids catch on that they have to do something quickly and they have fun following your instructions. When I get to 2 - 1, I stretch on the numbers in a silly way for the slower kids "uuuuuu-aaaaaaaa-nnnnnnnn... zeeeeeeeeeerooooooo" and the kids join in and shout it with me.
For discipline, I put 6 squares on the board, filling them in with silly smiley faces and sad faces based on class behavior, and do it without much commentary. When the kids are unruly, I silently walk to the board and add a sad face, or start slowly erasing a smiley face. Now when I filled in 3 sad faces, I would have some kind of "punishment (no stickers today!)" and vice versa, but with your little ones, the faces themselves might be enough motivation (?)
You might teach animals too. If you divide the class into several groups, "team elephant", "team monkey" etc, and tell a fun simple story with lots of drama, kids can do a gesture and the sound of their animal when they hear it mentioned in the story. Very interactive, kids pay close attention and recognize words.
Make sure that you are having fun too. Good luck!