Children with teachers vs with parents

A slightly different question here. I’ve been working as a kindergarten teacher for three years now, and I’m amazed at how differently children behave with their parents compared to us. With us, they are like little angels—well-behaved, cheerful, and full of energy. But as soon as their parents come to pick them up, they instantly transform into little devils. What’s the psychology behind this? It makes me a bit scared about having children of my own since I don’t have any yet.