What reading level is The case of the locked box?

The case of the locked box by Lewis B. Montgomery is at a Level 3-4 reading level. Recommended for Lower Grades readers (Ages 5-8).

What age is The case of the locked box appropriate for?

The case of the locked box is recommended for Ages 5-8. HootRating: 8C (Clear).

What genre is The case of the locked box?

The case of the locked box is fiction — Juvenile Fiction. Part of the Milo & Jazz Mysteries series.

Does The case of the locked box have any content warnings?

The case of the locked box has a HootRating of 8C (Clear). 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 The case of the locked box?

The case of the locked box by Lewis B. Montgomery is 106 pages (approximately 6,839 words).

Reviewed by HootRated editorial · Last updated May 18, 2026

The case of the locked box

Lewis B. Montgomery

The case of the locked box

Age Rating, Reading Level & Content Guide

by Lewis B. Montgomery

Illustrated by Wummer, Amy, illustrator

Milo & Jazz Mysteries

Reading Level 3-4 8C Ages 5-8 Balanced Read Page-Turner

The text is written at a 3rd grade reading level, the subject matter is intended for younger children (ages 5–8), and the content is gentle with no concerning themes.

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About This Book

Join Milo and Jazz, two young detectives-in-training, as they use smart STEM skills to solve the mystery of the missing money from a locked box. When Jazz faces a student court trial, Milo works hard to uncover the truth and clear her name. Filled with fun puzzles, hidden pictures, and brain teasers, this story is perfect for budding sleuths ready for chapter books.

Themes

Detective and mystery storiesSchool storiesFriendship

Quick Assessment

This is a Level 3-4 book with gentle content intensity. No notable content concerns flagged. Written for readers ages 5-8.

Why we rated The case of the locked box 8C

The case of the locked box is written at a Level 3-4 reading level across 106 pages (approximately 6,839 words). Strong independent readers around grade 4.5 can typically handle this book on their own; with parent or teacher support, The case of the locked box works for readers up to grade 5.5.

Read aloud, The case of the locked box takes about 46 minutes, which fits within a single read-aloud session.

We rate The case of the locked box as 8C ("Clear") 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, The case of the locked box explores detective and mystery stories, school stories, and friendship — these threads give the book room to mean different things to different readers.

Good fit for

✓ Children in the Ages 5-8 range — the maturity and attention span match the story's pacing.
✓ Reluctant readers who need fast-paced, hook-heavy stories to stay engaged.
✓ Kids drawn to stories about detective and mystery stories, school stories, friendship.
✓ Readers who fall hard for one book and want a long series to live in — there are 8 more books in the Milo & Jazz Mysteries series.