We have the children all sleep on cots (they're not that much more expensive than mats. But we got our's from another place that shut down and were selling them, so we got a pretty good price for them. $15 each, I believe, maybe less). We do not seperat the boys and girls. Infact, sometimes we alternate them, so that two boys aren't next to each other because they like play around and horse play instead of laying quietly.
The parents bring their balnkets and pillows on their first day of attendance and bring them home to wash on Fridays. I think it's good for them to have something familiar from home to sleep with. They seem to settle down faster, too.

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