If you find it odd that Kate McKinnon chose her first book to be for middle-grade kids, the former “Saturday Night Live” star says, think again.

“I find sketch comedy and middle school to be very similar,” she said recently over Zoom. “There can be an unabashed silliness in middle grade that I have found only in sketch comedy.”

“The Millicent Quibb School of Etiquette for Young Ladies of Mad Science,” now available, follows the three Porch sisters, Gertrude, Eugenia, and Dee-Dee, who feel that they don't fit in their hoity-toity town. They live with their snooty aunt and uncle and equally snooty seven cousins — all named Lavinia. When the Porch girls are kicked out of school, they find a new mentor in an outrageous scientist with worms in her hair named Millicent Quibb.

In a Q&A, McKinnon spoke about her childhood and "The Millicent Quibb School of Etiquette for Young Ladies of Mad Science,” which she wrote mostly from her bed. “I ended up staying in bed for a year, basically,” she laughed. The plan is that this is book No. 1 in a series.

Answers have been edited for clarity and brevity.

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AP: Some themes in this book are about identity. It would be fitting if you wrote this while filming “Barbie.” Did you?

MCKINNON: I started writing this before “SNL," and worked on it throughout, whenever I had a moment, and picked it right back up after I left. I like weirdos. I am a weirdo. I like playing weirdos, and I like reaching out to fellow weirdos. And this was just another venue for doing that.

AP: What was it like going from the hectic, repetitive pace of “SNL” to writing fulltime?

MCKINNON: I was surprised by how much it felt like performing. I felt like I was improvising. It felt like sitting in a room and writing a sketch for “SNL,” but then you just have a lot more time to revise. I absolutely love it. I’m an introvert, so writing by myself does not bother me. As much as I miss my colleagues, it suits me in some way.

AP: In the book, the Porch sisters find a true mentor in Millicent who encourages them to be who and how they want. Who was your Millicent growing up?

MCKINNON: I had parents who celebrated my weird, little activities and let me take the clamshells home when we had linguine and clams at a restaurant. They bought me little archeological kits and just really fostered whatever esoteric interest I had. I also had teachers who helped me and supported me. Sometimes a magical adult swoops in and fosters the gifts you were born with that other people are telling you are bad.

AP: The book is silly and funny. Did you ever make yourself laugh while writing?

MCKINNON: I do. I enjoy names. I think funny names are a whole art in and of itself. I was proud of the names I came up with.

AP: Talk about narrating the audiobook.

MCKINNON: That was some of the most labor-intensive performing I’ve ever done. I’ve done plenty of voice overs, but you’re doing every line. When writing, the first thing I had to do was come up with voices for all of the characters. With anything I’m like, ‘What’s the voice?’ I have to start with that. Then you decide the hair and the clothes and that’s all you need to know. I knew what all of the characters sounded like going in.

AP: Will you go on a book tour and meet your readers?

MCKINNON: I am going on a cross-country trek and I am so beyond excited. At 12, I was getting messages from the culture and from some of my peers that I was not OK the way I was. To have someone look at you and say, “Hey, the thing that you think is weird about you, that’s actually what’s going to save you as a grown up. And that’s actually what’s going to help the world-at-large.” To give that to someone else would be the honor of my life.