If your families aren't in church, then help them to continue with spiritual formation wherever they are. Here are some great resources to help you do that.
Candle Press has a series call "To Go" which has one sheet a week that can be emailed to parents. Each week contains an easy lesson with everything parents need to read the Bible, talk about it, remember it, and play a fun game. These easy-to-use lessons help give parents ways to talk about faith with their children using things they would have in their home. There are all kinds of topics to pick from. These are great for Baptismal Preparation as well.
Vibrant Faith at Home has all kinds of easy lessons for parents to do with their kids - both young children up through high school. These are designed to take 10 minutes so they can be done anywhere. But these great resources help parents have important faith conversations and explore the Bible in a fun way. There is an app for this as well - and everything is FREE. The online lesson plans would be great for a summer Sunday school as well.
Weekly and/or Daily Text to Parishioners are EASY with this app: Remind 101 is a free app used by teachers to send reminders to parents and students alike. Why not use this service to send a spiritual text to your parishioners and keep them connected spiritually through the summer. Users sign up online for the service, and the organizer simply goes online to set up the texts. You never have to enter everyone's phone into your own phone, and there are no privacy concerns. Check out the service at www.remind101.com.
Visiting other churches on vacation: Keep a bulletin board at church and post a bulletin from another church they visited while on vacation. Make it game to see who traveled the furthest, or what was the most unusual service someone went to. Help foster some discussion about what they saw, what they liked, and how that church is different or similar to your church. Better yet, use online tools -- encourage your parishioners to post on the church's Facebook page what churches they might be seeing on their travels.
Vacation Bible School - It may be too late for your church to plan something for this summer, but encourage families to take advantage of these summer programs wherever they may be.