Show the children an apple and explain that, just like God, the apple has three parts that work together to make the apple whole --- the skin, the flesh and the core. The skin provides protection for the soft flesh. The flesh is the sweet part for eating and the core contains the seeds, which help the apple reproduce. The apple has three parts but it is one fruit, just like God is one person with three parts, one of which is the Holy Spirit. The core is like the Holy Spirit, because just as the seeds reproduce to make more fruit, the Holy Spirit comes to plant the seeds of God's truth in your heart to spread the good news of Jesus to others.
Ask a child to press the "on" button of a battery-operated radio, CD player or digital music player. Leave the batteries out and do not plug it into an electrical socket, speakers or music player dock, but do not mention the lack of power to the child yet. Explain that this device is designed to play music and ask the children why it isn't functioning properly. Examine the device together and elicit the discovery that the power source is missing. Hook the device up to the power and speakers and press the power button again. This time you should hear the music. Explain that the Holy Spirit is like a believer's power source. Without the power of the Holy Spirit, people cannot do the things that God designed them to do. When the Holy Spirit comes to live in you, he empowers you to function the way God created you, so you can do the things he asks you to do.
Place some ice cubes into a cooking pot and place it on a hot plate, stovetop or camping stove and turn on the heat. Ask the children what they think will happen. Watch the ice melt and note that whether it is in solid or liquid form, it is still made up of two parts hydrogen and one part oxygen. Ask the children what happens to the water when you continue heating it. Watch it turn into gas and disappear. Explain that even though you can't see it anymore, the water is still in the air. You cannot easily see the gaseous form in the air, but you notice the effect that it has on the things around it such as rustling leaves. In the same way, you cannot see the Holy Spirit, but when someone lets the Holy Spirit work through her, other people notice the difference in the way she acts and treats other people.