Here are some quiet signals I’ve heard over the years:

Practice Map Directions.  Teacher: “Point North” (students point). “Point East” (students point)… in different orders so the students learn the directions needed for using maps.

Eyes On Me. Teacher: “1 2 3 eyes on me.” Students: “1 2 eyes on you”

Counting Down. Teacher starts counting backwards from 5, getting quieter and quieter with each number.

Do This. Teacher does simple actions such as touching nose, folding arms, etc. while quietly saying “do this” with each action. Soon students are looking around for the source of the directions their friends are following and it gives the kids something to do until everyone is ready.

Claps. Teacher claps out a rhythm and students must copy. Some students have a specific rhythm they use (teacher claps the first part and students finish the rhythm).

What signal do you use? Please share your ideas by commenting!