There has been some great ideas on this topic over at the NAEYC Open Discussion Forum. You have to have a membership to post, but not view the threads as far as I know. Here is one: https://hello.naeyc.org/commun...amp;tab=digestviewer
We subcontract our Head Start and ECEAP (WA state-funded version) through PSESD and I am attaching the procedures for all hazards preparedness drills. The last page of the document covers lockdown expectations.
Hopefully this helps!