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Notes for the Instructor

The Cookie Jar Mystery is a project-based learning experience that asks your students to complete a series of activities in order to figure out who ate Mrs. Randall’s cookies. Students will learn about specialized jobs, techniques and tools employed by forensic scientists. The more realistic the mystery seems to your students, the more engaged and invested they will be in learning the information and conducting the science experiments. As the instructor, your enthusiasm and investment is key!

This introductory lesson is focused on observation skills. In the first activity students will be challenged to see how many details they can notice and recall. You will guide students through observations, discussions, and an analysis of two different photographs. Then, students will be introduced to The Cookie Jar Mystery with a photo taken from the crime scene. Students will utilize their powers of observation to begin to unravel the mystery. Taking in details at the scene and being able to recall them later is a key skill for investigators. Students will realize that these skills can be strengthened with practice and by implementing helpful strategies.

In the second activity, students will use their powers of observation to compare and contrast the note left behind at the cookie jar crime scene and handwriting samples taken from the four suspects. Notes or other written documents that are part of the evidence at a crime scene, usually with an unknown or unverified author, are called questioned documents. Handwriting experts called document examiners are called in to compare the questioned document to handwriting samples taken from the suspects.

Handwriting samples can be collected in two ways. The first way is called request writing, and is obtained from a suspect during the investigation and with a witness present. The second type of sample is called non-request writing. These are samples that were written previously, before the person became a suspect in the investigation. If the authorship can be verified, a non-request writing sample is preferred. This is because request-writing samples can vary from a person’s true writing, possibly because the person is nervous about being questioned, or perhaps because he is deliberately trying to change his handwriting.

In forensics, experts study the unique characteristics and nuances of an individual’s handwriting, including its form, line quality, arrangement, and content. They also look at the type of pen and paper used. Often the work of a document examiner is to notice differences rather than similarities. This is especially the case if a document is suspected of being forged, or written by someone other than the assigned author. While it is possible to copy someone else’s writing, it is almost impossible to erase all traces of our own individual writing style.

Some characteristics of writing are visible to the naked eye, meaning they are visible without the use of any additional tools. However, forensic scientists often use hand lenses, microscopes, and special lighting to analyze handwriting as well. These tools can highlight inconsistencies in the paper or ink of a note. Angled lights can show indents on the paper that might suggest a signature was traced. Backlighting reveals eraser marks and use of correction fluid. The observations made by your students today will be with the naked eye.

The activities in this lesson address Next Generation Science Standards practices of Planning and Carrying Out Investigations and Analyzing and Interpreting Data. In addition, they address Common Core Learning Standards. See the appendix on page 105 in the Instructor’s Guide for more details.