What reading level is Astrotwins?

Astrotwins by Mark E. Kelly is at a Level 4-5 reading level (Lexile 770L). Recommended for Middle Grades readers (Ages 9-12).

What age is Astrotwins appropriate for?

Astrotwins is recommended for Ages 9-12. HootRating: 9LS (Light — Social).

What genre is Astrotwins?

Astrotwins is fiction — Juvenile Nonfiction.

Does Astrotwins have any content warnings?

Astrotwins has a HootRating of 9LS (Light — Social). No specific content flags noted. On HootRated, every book is rated across four dimensions — emotional, physical, social, and thematic — to help parents make informed choices.

How many pages is Astrotwins?

Astrotwins by Mark E. Kelly is 210 pages.

Reviewed by HootRated editorial · Last updated September 7, 2026

Astrotwins

Mark E. Kelly

Astrotwins

Age Rating, Reading Level & Content Guide

project blastoff

by Mark E. Kelly

Reading Level 4-5 9LS Ages 9-12 Balanced Read

The text is written at a 4th grade reading level, the subject matter is intended for middle graders (ages 9–12), and the content is gentle with no concerning themes.

Find on Amazon Listen on Audible

We may earn a commission from these links. Bookshop.org supports independent bookstores with every purchase.

About This Book

What if you and your twin decided to build a rocket from scratch? Imagine summer days filled with sparks, teamwork, and a little sibling rivalry as you chase a dream that feels out of this world. But can two brothers and their friends turn their big idea into a real launch before their grandpa’s patience runs out?

Themes

Family Friendship Science & Nature AdventureTwins

Quick Assessment

Astrotwins is a middle-grade fiction novel inspired by the childhood of NASA astronaut Mark E. Kelly and his twin brother. It tells the story of two brothers and their friends who decide to build a rocket, highlighting themes of teamwork, sibling dynamics, and perseverance. Suitable for ages 9-12, the book offers an engaging introduction to science and technology within a relatable family adventure context.

Why we rated Astrotwins 9LS

Astrotwins is written at a Level 4-5 reading level with a Lexile measure of 770L across 210 pages. Strong independent readers around grade 5.5 can typically handle this book on their own; with parent or teacher support, Astrotwins works for readers up to grade 6.5.

We rate Astrotwins as 9LS ("Light — Social") because the content sits in the "Gentle" range — no conflict beyond everyday childhood experiences. Across our four dimensions (emotional, physical, social, thematic) the book reads as evenly gentle; no single dimension stands out as a concern.

No specific content flags were raised by community reviewers, which is consistent with the gentle intensity score.

Thematically, Astrotwins explores family, friendship, science & nature, adventure, and twins — these threads give the book room to mean different things to different readers.

Good fit for

✓ Children in the Ages 9-12 range — the maturity and attention span match the story's pacing.
✓ Patient readers who enjoy slower, character-driven stories.
✓ Kids drawn to stories about family, friendship, science & nature.

Maybe not for

! Readers whose emotional readiness lags behind their decoding skills — this book's intensity outruns its reading level, a classic "gifted kid" mismatch.
! Reluctant readers who need a fast hook — the pacing here rewards patience.