Not sure if this is too old for your group but have them line up in order of their birthdays without talking. You can make it harder by saying no obvious hand signals, like number of fingers. Then they have to come up with something creative for the month of their birth (like a Jack-o-lantern or flag).
This one's not very active but it's a good transition activity: break them into teams and give each team an ordinary object like a coat hanger, paper clip, jump rope, whatever. The goal is to come up with as many uses as possible for that item and demonstrate some of them to the other teams.
Using blocks or legos, build a structure. Give them (or break them into teams) the same building pieces you started with. Line them up away from the structure (so they have to move). They have to duplicate your structure but each kid can only move/add/replace one piece at a time. If you do teams, it can be a race. No talking.
Do they know each other? A name game is good - have them choose an adjective that starts with the letter of their first name. Groovy Gary or Marvelous Mary. In a circle, give them a ball and they pass the ball to each other, saying the person's name before they pass the ball. So, Gary says "Marvelous Mary" and passes the ball to Mary. She says "Jumping Jim" and passes it to Jim and so forth.
