Ask: Who are you? Have children say every thing they can think of that answers this question? If no one answers, "I Am A Child of God," ask the question again, "Who are you?" then guide the answers.
“all of [us] are children of the most High” (Psalms 82:6).
“God created man in his own image” (Genesis 1:27)
Show a picture of the First Vision. Who are the people in this pictures?
Joseph Smith saw Jesus Christ and Heavenly Father in a vision.
Most, if not all, of of us today haven't seen Heavenly Father in person, but we can find out what He is like, by reading the scriptures and by seeing how earthly fathers interact with their own children.
Have children describe their father (or other male figure in their life). Write or draw the descriptions down. When the list is a good length, ask: "Would you use these words/pictures to describe Heavenly Father? Could we add or change some words?"
Heavenly Father has given us many things that we can enjoy right now.
Can you think of anything Heavenly Father has given you?
An earthly family A beautiful world for me
Talents Church leaders and teachers
The scriptures Answers prayers
Here is a link to a Scripture Box, it list scriptures that will help remind the children that they are "A Child of God"