Tell a child that if he/she does 10 push-ups or something else of your choice, you promise (use the word “promise” several times during this lesson) that you will give them a pack of chewing gum.
After the child has done it, tell him he’s done a good job, but you’ve changed your mind and only give him one piece of gum instead of the whole package.
Ask another child and do the same (the children will certainly say “but you promised”). Give several “excuses” for not fulfilling your promise.
Then call the same children and ask them how they felt when they did everything you asked them to do, but you didn’t keep your promise? Give each child a full pack.
Explain that the only one who will never break his promise is the Heavenly Father. Show the children a Bible and tell them that this book is full of wonderful promises and that if we do our part, He will do His, it is promised!