As parents, there are a varieties of ways you can help your entire family during a season of focused prayer and fasting. Here's a few tips and resources:

• Explain what you are doing, why and for how long. Many use mealtimes for this.
• Prepare ahead for any hobby, time or food changes they may not be used to.
• Invite them to pray about giving something up as well.
• If they do, start small and give them grace (and yourself).
• Celebrate what God is doing with your family.

Podcast:

Family Life Today - Family Fasting

Articles:

Fasting With Young Children

Fasting - Teaching Kids Spiritual Disciplines

Books: 

Revival Starts Here by Dave Clayton

Hunger For God by John Piper