The best way that we have found to communicate with our parents is through email. Especially for requirements that need to be done at home. We have found that the notes we send home with the boys may or may not be seen by parents. My co-leader and I like to meet quickly on Sundays so we usually send an email to all the parents on Sunday. The email tells them what we have done in our last den meeting, what they need to do at home, what is coming up in future den or pack meetings, and what requirements of Faith in God (LDS church) correspond to the activities we have worked on so the parents can sign off in the Faith in God booklet. I think it is nice for the parents to have announcements in email form so they can refer back to them for dates in the futures.
I have heard that other leaders like to send a weekly email and follow up with a text to the parents the day of den meeting if there are any reminders like a change of location or something the boys need to bring with them.We email weekly, then give each parent a phone call if we need to remind them of something.
We spoke with our parents and this seems to work the best for them...and us!