C. Michael Patton of Parchment and Pen has some excellent pointers and even a couple of visual aids for teaching the doctrine of the Trinity. And, having recently addressed the subject with a group of seven- to thirteen-year-olds, he is almost certainly a more doctrinally assured Christian than me. Bottom line: quit using stupid analogies that only teach trinitarian heresies. Second bottom line:
One more thing. I often tell my students that if they say, “I get it!” or “Now I understand!” that they are more than likely celebrating the fact that they are a heretic! When you understand the biblical principles and let the tensions remain without rebuttal, then you are orthodox. When you solve the tension, you have most certainly entered into one of the errors that we seek to avoid.