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The Case of the Chocolate Egg

In this project, elementary students explore the structures and features of picture book mysteries and use this knowledge to write and illustrate an original collaborative mystery in a ’big book’ format.



Before producing their collaborative mystery, the Cycle 2 students at Carlyle Elementary School in Montreal:

  • brainstormed what they already knew about mysteries (activated prior knowledge)
  • identified the features that helped them recognize a mystery by listening to Read Alouds and participating in class discussions
  • learned common mystery terms and vocabulary to help them read and discuss illustrated picture book mysteries with classmates
  • worked in pairs to explore how the images in the mystery added to the story
  • found evidence that their book fit into the mystery genre and shared their observations with the class



The students worked in small groups to build a mystery around a school-related problem. (The school secretary reported that candy was missing from her desk in the office.) They brainstormed possible plot lines and characters, thought about possible clues and red herrings to keep the story exciting and came up with ideas for the solution to the mystery.

Groups shared their ideas, and the whole class selected the story idea that would become the collaborative big book. They made decisions about the way the characters would look and dress, as well as the setting, so that there would be continuity throughout the book. A large chart was filled in with important details about the setting, characters, clues, distractions, plot and conclusion of the mystery.

The mystery was divided into 5 sections or chapters and each group selected the part of the story they wanted to write and illustrate and made a plan/storyboard.




Students, working both independently and in collaboration with the members of their group, wrote and illustrated their sections of the book.

Since it was a collaborative project there were many opportunities throughout the writing process for groups to share their drafts with the class and teacher in order to receive feedback and to keep the continuity of the story. Transitions from one chapter to the next were decided on by the whole class and recorded by the teacher.

When the final draft was edited and revised the big book was put together.



The students celebrated the classroom publication of their collaborative mystery. They shared their mystery with other classes. It became part of the class library and was a popular home reading choice.


Additional Resources for Working with Mystery Genre

What’s in a Mystery? Exploring and Identifying Mystery Elements

Genre Study: A Collaborative Approach

It’s a Mystery


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My goal for this project was to allow my students to reconnect with some of the favourite childhood picture books that had an impact on them, as (...)