If your children have an interest in computers, you might ask for their help surfing the net, and checking databases for your surnames. Or maybe they can help you figure out and enter data in a new genealogy program. Share your discoveries and try to make them as interesting as possible. Illustrate your relationship with a pedigree chart. Show them pictures if you have them.
Many times connecting a face with the relationship can be helpful.
Tell them stories and if you have older relatives that might be willing to share some stories, you might find you have encouraged a closer relationship between the generations. Do your homework. Read about the times that your ancestors lived in and connect your ancestors with stories from history. A great time for this might be while you are helping them with their history homework. Tell them about your relatives that may have been involved in various wars, large migration movements, or other events in history.