Give each kid three sticks. Each time a kid talks out of turn, take a stick away. Lose all three and talk out of turn again, get a red stick. Each red stick = lose 5 mins of recess (or whatever consequence you choose). Hmm.... Something to consider.
Considerate Classroom: Early Childhood Special Education Edition: Tour Our Classroom's Independent Work Area Sand timers with different intervals for work time, breaks, cool down time, etc Could be used in gen ed as well of course