I don't know if five is too young for a drop off but, I would check out Circle Yoga on Northhampton street near the chevy chase circle. I have teens so I didn't look at the younger classes. I would start there.

do any yoga studios have drop off kids yoga for five year olds on the weekends? I have seen a couple family yoga classes, but my kid really wants to take yoga with other kids (like in school) and not a family class with me.