When I was young my mom helped me and my siblings make a missionary prayer book.
We would paste a photo/prayer card of the various missionaries our church supported or just of missionary friends that we knew personally and each night at family devotions would bring our missionary prayer book with us to help us remember all those missionaries.
We would also have assigned prayer nights - Mondays would be for the "Missionaries" , Tuesdays for our government leaders, Wednesday for our church leaders, Thursday would be for the unsaved, and Fridays we would pray specifically pray for our "Friends & Family" those that were sick, etc. - of course the list of who we prayed for when wasn't set in stone. We of course could pray for sick friends or family members on Monday or any other day of the week even though the "assigned" day was Friday. The prayer list was made to help us faithfully pray for those around us both here and around the world.
Perhaps this week you can help your child make their own missionary prayer book (or make one for yourself!). Be creative. Gather up photos and prayer cards of missionaries you know and that your church supports. Those of you that have a creative touch - find scrapbooking paper and stickers (e.g. globes, kids from other countries, Bibles, etc.) to put into your book. You could also look through old magazines or newspapers for "mission" themed pictures. If you can't find any good stickers in the craft stores - try searching for free clipart on google - print it out and glue it into your book. Have fun.
You can also type or write out a list of e-mails/addresses/birthdays of the missionaries - so you can use as a reference later in the year for correspondence. You might even want sign up to receive their prayer letter so you can know how to better pray for them and their family.
Set a time during the day/week to bring out those prayer books and pray for those missionaries together with your child(ren). Take that time to explain what missionaries do and as a child even though they are young they can be a missionary too - right where they live!
Here are a few other things that I have done:
-Written a different country name on every single day of my 12 month wall calendar to remind me to pray for those countries - whether or not I know of a missionary serving there or not. That God would soften hearts of the people there to accept His word and for those that He would call/has called to go take the salvation message to those people groups.
-Check out books from the library (or do research online) on those certain countries of which you are praying for that day/week. Type out a paper with facts/brief info. on that country and people group and start yourself a geography note book.
Here is something I thought of doing, but wasn't able as I couldn't find a paper map (the only ones I have are plastic):
Finding a large paper world map to post on the ceiling of my bedroom with photos of missionaries surrounding it, as a reminder to pray daily for each one and for the people in the countries they serve. You could of course adjust and post the map down on the wall and doing the same thing with taping up pictures of missionaries around the boarder of the map.