Whether you call it ‘family devotions’, ‘family worship’ or ‘family Bible reading’, the practice of parents regularly reading the Bible and praying with their children can be a vital part of bringing our children up in the training and instruction of the Lord (Ephesians 6:4). It does not have to be long or elaborate, better to be short, simple and regular. Ligon Duncan and Terry Johnson offer these helpful thoughts:
A whole host of practical questions and problems come to mind once we determine to begin family worship. How long should it last? It should be regularly brief, as little as ten minutes when the children are very young. Gradually, it will run a little longer as they grow older and conversations strike up. Don’t kill it by trying to go too long. Pace yourself. Regularity and repetition is the key. When should we do family worship? When it works – morning/breakfast, suppertime or bedtime are the three most common times. What about the obstacles to starting and continuing family worship?… There are dozens of potential hindrances: lack of discipline, lack of sense of the importance of family worship, lack of experience of family worship in one’s own upbringing and more. But above all, the enemy is idealism. You have this picture of a Puritan family sitting around the table attentively and reverently reading the whole book of 1 Chronicles at a sitting, singing half the Psalter from memory, and praying for ninety minutes, and then you look around your table and your wife is rolling her eyes, your two-year old is throwing left-over spaghetti around the kitchen, your eight-year old is making faces at her sister and your teenager would rather do calculus. Do not let the gap between the ideal and the reality stop you! Those unattentive children will grow up and thank you for persevering, and the memories of a father who loved them enough to make that kind of an effort will etch a permanent affection in their hearts. 
The two most important components of such family times are:
Bible Reading: Read a short section from the Bible (as the children grow they may like to share in reading aloud), then ask your children some simple questions. You may like to read from the passage you’ve already read privately that day, so you can prepare and anticiapate their questions. If you’d prefer help, there are many resources, including Table Talk , various books by Susan Hunt and Long Story Short by Marty Machowski. There are also some good Bible overviews for younger children such as the The Big Picture Story Bible .
Prayer: One or both parents can pray. As your children grow, they may like to pray too. Don’t be too concerned if they don’t want to pray sometimes, or they pray the same thing every day. Let them learn over time from your example of asking your Heavenly Father. You may also teach your children to pray by reading prayers from the Bible, like Jesus’ model prayer (Matthew 6:9-13), Psalm 51, Psalm 121, or Psalm 145, or using other model prayers written by Christians. As they grow it can be helpful to pray for missionaries you support or use a persecuted Christians prayer guide to grow a perspective of God’s work in the wider world.
You may like to add one or more of the following components:
Scripture Memory: Choose a short passage and read it regularly. You will be amazed at how quickly your children will learn it by heart. Encourage them to say it out loud, it may have the added benefit of helping you memorise Scripture! Passages to consider learning include: Psalm 19, Psalm 23, Proverbs 1:7-10, Matthew 16:24-28, 1 Corinthians 13, Ephesians 4: 25-31, 6:1-4, and 1 Peter 2:21-25. Alternatively, there are various resources to help you begin, including: My First Book of Memory Verses and My ABC Bible Verses .
Theology: You may like to supplement your Bible reading by teaching your children some of the important truths about God. Helpful resources include: My-1st Book of Questions and Answers, Big Truths for Little Kids , A Catechism for Boys and Girls and Big Truths for Young Hearts .
Singing: Some families sing as part of their devotions, others prefer to sing to CD’s in the car or at other times. We’ve enjoyed CD’s by Colin Buchanan , Emu Kids and Sovereign Grace Kids ,which all celebrate rich doctrinal truths with practical applications helpful for children. Children can enjoy singing ‘adult’ songs too.
To conclude, here’s an encouraging testimony from a young man remembering his father praying with him: I came from a Christian home where I was taught to love the Lord at very early age. One of my fondest memories as a young boy was having my father pray for me at bedtime. Each night he would pray: “Father in heaven, I pray for my son—That you would bless him and keep him, and give him a good night’s sleep. I pray that he would grow to be a just and upright man, and that he would never know a day without you. In Jesus Name I pray, Amen.” I remember one night at about age 9, my dad bent down to kiss me after praying and noticed that my eyes were tearful. He asked, “Why are you crying, son?” And I answered, “Because I’m happy…” Little did my father know that the Lord was dealing with me in His own peculiar way. For some time, my soul had been restless because of sin in my life and my need to be forgiven. That night, when my father prayed the words, “that he would never know a day without you…” I knew for the first time that I knew the Lord Jesus—and that made me very happy. 
It’s important that Christian parents model the gospel of Jesus in our lives, and look for the variety of teachable moments that arise in living together as a family, yet along with these, the simple act of regular Bible reading and prayer with our children can have a profound impact by God’s grace.
 For some examples, see: http://trevinwax.com/2008/08/12/bedtime-prayers-with-our-children/