Is your sister real or pretend?

Recently Elisabeth said to me, "My sister is going to school." I figured that this age would be a good time to teach the difference between real and pretend. So I asked her, "Is your sister real or pretend?" Elisabeth replied, "She's real."

Now, I thought, she has heard the words real and pretend. I can explain them so that she knows what they mean. So I said, "Real people are people that we can meet and know. Pretend people are people that we make up in our heads. Is your sister real or pretend?"

Elisabeth replied confidently, "Real. She's at school."

Clearly my lesson wasn't quite as effective as planned.