This is the STEM chapter book series done right. Instead of feeling like vegetables disguised as dessert, the Questioneers books are genuinely fun mysteries that happen to teach engineering, science, and critical thinking along the way.

The 4.9 Amazon rating isn't just parent wishful thinking—kids actually like these. The mysteries are engaging (who doesn't want to know why pants are floating toward space?), the characters are distinct and likable, and the failures-then-persistence arc feels real without being heavy-handed.

What makes this collection work is that each book showcases a different talent, so kids can find their entry point whether they're into building things, asking questions, drawing, or organizing people. It's also genuinely diverse in a way that feels natural rather than checked-box.

The only caveat: six chapter books is a lot. Some kids will inhale the whole set in a week; others might prefer to try one or two first. But as a bridge from picture books to longer reading, this is solid gold for the 6-9 crowd.