Tuesday, October 11, 2016

The Case of the Missing Cake: Using a CSI Lab to Teach Chemical and Physical Changes

Physical and Chemical Changes CSI Lab Activity for Middle School Science
Everyone loves to solve a mystery, so The Case of the Missing Cake CSI Lab gets students excited to observe and classify physical and chemical changes!

The CSI Lab Scenario will definitely engage the students and make learning about physical and chemical changes much more interesting.

But, if you want to amp up the engagement, then you may want to decorate your classroom as a crime scene.

Add the caution tape.  Have an empty cake plate with a trail of white powder on the counter.  Dress up as a detective or crime scene investigator.  The more you sell this activity, then the more excited your students will be about learning the basics of chemistry.


Imagine being a student in your classroom when the room is staged like in the photo above.  Exciting, right?  In an instant, you have already captured their attention.  Then, you can explain the case.  In this lab, a cake decorated by a famous baker has gone missing from his bakery overnight.

It is up to the students to solve the case!  

Physical and Chemical Changes CSI Lab Activity for Middle School ScienceThree suspects were found with white powder residue on their clothing.  So, the students must test samples of known and unknown substances to determine which suspect was the culprit.

The students will then observe what occurs when testing the known white substances with water, vinegar, and iodine.

Did it dissolve?  Did it fizz?  Did it turn colors?

Once the lab group discusses what was observed, then they classify the observation as a physical or chemical change.

Students will then be presented with unknown samples collected from the crime scene and each of the suspects.  They will then need to test these unknown samples as they did the known samples.

Once the results have been collected, then the data analysis begins.  You may have to walk through the data analysis with your students.  Help them be able to compare the known substance results to the unknown substance observations.

Can they determine which substance is which based on the observations?  Which sample collected from the suspect matches the observations made with the crime scene sample?  Who was the cake thief?


A photo posted by Esther Alvarez (@alvrze) on

The fun part, as a teacher, is that you can always have some tricks up your sleeve.  If you are conducting this lab with more than one class, then you may want to switch up the crime scene sample.

The different classes will yield different results as to which suspect is guilty of stealing the cake!  This will keep the students on their toes and avoid any spoiler situations that are lurking in the hallways or cafeterias.  There is always one student who can't wait to share the verdict with the others!

This lab helped students collaborate with others, classify the observations as either physical or chemical changes, and encouraged higher level thinking with the analysis of the collected data.  Plus, it got students excited about science!  Yes!!

Physical and Chemical Changes CSI Lab Activity for Middle School ScienceAre you interested in conducting this lab in your class but don't have the time to create the lab handouts or corresponding presentation?  Check this resource out in my TeachersPayTeachers store - it is available in PowerPoint and Smart Notebook formats.

Special thanks to Esther Alvarez!  She is a rock-star teacher in Texas who has conducted this lab in her middle school science class for a few years, and is always so nice to share the photos with me!  You can follow her on Instagram and Twitter.
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