Years ago, when I was a teenager I saw Lee Earle lecture. He did his gumball prediction and then warned that it’s not a kid show trick and that mentalism doesn’t work for kids. Lee said something like, “before you can read someone’s mind, they must first have a mind”. That’s a great quote, but it’s wrong.
You absolutely can do mentalism for kids, but ultimately it comes down to how you frame it. In my library / summer camp show for this year I do three mentalism tricks.
They aren’t framed as “mind reading” and that’s what makes them work, but they are still 100% mentalism. All three are essentially predictions.
One of them I used a Cootie Catcher / Fortune Teller to determine what I’m going to have for lunch or dinner that day.

Another is a card prediction followed by a series of coincidence effects. The third is a strange happening, which is really a multiple revelation of predictions. All three of them are highlights of the show and frequently mentioned when I ask kids in the autograph line what their favorite tricks were.
Don’t be afraid of mentalism for kids, you just need to make it fun and relatable to them.
-Louie