Your children might enjoy this charming story: “A child’s prayer can save a (duck’s) life.” While one can never spend too much time discussing God’s answers to prayers, your children may be ready for the next step: adding repentance or fasting to prayer.
Instead of four steps of prayer (address Heavenly Father by name, thank Him, ask Him, and close in Jesus’ name), consider the FIVE steps of prayer (add repentance as a vibrant, daily part of prayer). Here’s a downloadable handout. (See also “Personal Prayer Lesson Plan – with visuals for children, especially those with Special Needs.”)
Or your children may be ready to be introduced to Fasting for Beginners, adding fasting to prayer as reverent communication between God and me.