Nephew (almost 4 years old): What’s the first number in ninety?
Me: Nine. That’s why it’s nine-ty.
Nephew: What’s the first number in eight?
Me: There’s only one number in eight, that’s eight.
Nephew: What is one?
Me: …Is that a philosophical question?

You know you’ve been in science too long when answering questions asked by 4 year olds becomes hard. “Why is the sky blue? Well…..”