child psychology

On Wednesday mornings I've been volunteering at the preschool that's at my church. Last week we had to ask the kids a list of questions... questions like if they know what their last name is. One of the questions was if they have sisters or brothers, and how many? It was interesting to see how not just one, but quite a few girls reasoned out how many sisters they have. "Well, I'm a sister, and my sister is a sister, and my mom is a sister. Three. I have three sisters."