Choose three to participate and ask them to think of a prayer request. Tell them that because you're God, you'll be answering their requests today. (before hand prepare three small slips of paper with "yes" written on two of them and "no" on the other one. Pass the "answers" out (have the yes answers given to the first two kids).
Ask the first child to open their answer. Rejoice with them as they reveal the "yes" they've received. Award that participant with a fun sized Snicker bar. Do the same with the second.
As you move excitedly along to the last participant, have them reveal their "no". "Wow, I'm so sorry that you didn't get what you thought you needed. That really stinks." Then, bust out a huge KING SIZED SNICKER bar to the delight of your audience explain that sometimes God's plans for us are far better than anything we could have asked Him for. We can trust Him with our lives.
How about you? Have you used candy bars as object lesson before? Tell us!