My favorite subject to teach is Forensic Science. It is the perfect mix of applied Biology, Chemistry, Math, and the Yuck-Factor that students just love!
And no topic in Forensic Science has more ‘yuck’ than the study of dead bodies. Students look forward to this unit all year! They are never disappointed.
Reading, hearing, and seeing pictures about Autopsies just doesn’t cut it. Students need hands-on experience to really learn and appreciate the work of Forensic Medical Examiners.
But murder victims are hard to come by for use in the classroom!
So in my forensic science class, we use Rats. This post is all about how to turn a Rat into a murder victim!
Choosing Rats for the Classroom
Rats are great in a forensic science class for a few reasons. They are
- inexpensive – relative to other possibilities, such as fetal pigs or cats
- large enough to see their insides
- anatomically very similar to humans
- have complete, and fully formed skeletons – unlike fetal pigs which sometimes have a lot of cartilage
The best deal on preserved rats is from Flynn Scientific. These are great if you are just interested in the Autopsy of the rat.
But if you want to get the most out of the experience, go all the way and use your rats to teach forensic entomology too!
For that, you will need rats that insects are happy to feed on. Frozen feeder rats can be purchased at some pet stores, and even delivered straight from Amazon. For large frozen rats they are about the same price as the preserved ones.
Setting Up the Murder Victim
This activity can be used to reinforce the concepts of:
- Wound analysis – post vs. peri mortem
- Livor mortis
- Evidence of asphyxiation
- Evidence of drowning
- Time between death and the last meal
- Wound ballistics
- Practice weighing and examining internal organs
Here are the details for getting rats ready for your young Medical Examiners!
If time allows (and your administration is okay with it!) stage the ‘victims’ somewhere on campus. Either have your students collect the bodies themselves or you can take pictures of the crime scene and provide them to your MEs as they file their reports
If you are using the frozen feeder rats, they will attract flies after they thaw out. If you are interested in using real entomological evidence for your students, this is a great way to do it. Depending on the weather, it may take just 24 hours to have maggots on your bodies.
Students will need to collect the largest maggots to measure, determine the developmental stage, and then use weather information to calculate the accumulated degree hours.
Tell students to just assume all of the maggots are the same species of green bottle fly, and to do their best to calculate post mortem interval. The goal is more to practice the concepts than to get a super accurate PMI! Maybe offer bonus points to the students who are the closest!
Be warned – decayed murder victims smell very bad! And are very, very gross. Some students may not be able to handle examining and dissecting a smelly body with maggots crawling around it. Be ready to give them a rat that has not sat outside, or an alternate assignment.
Also, for the sake of your students and your colleagues, consider holding the dissection of decayed rat bodies outside the building. You do not want your room (your whole hallway!) to smell like death.
Alternatively, you could set out one single rat and have any interested students collect and analyze the maggots, but allow all students to actually do the dissection on rats that have not started decaying!
If you or your students can not stomach the smell (boy does it smell!) and handling of actual Crime Scene Insects, that is okay! You can still incorporate Entomological evidence. Find plastic insects or make them! Making ‘insects’ can also give you more control over the outcome of the Post Mortem Interval calculation!
Squirts of hot glue are perfect for maggots, or use pipe cleaners cut to particular lengths to represent maggots at different stages of development. Have students measure their length and determine what stage they are in to figure out the Post Mortem Interval
Rub some blue food coloring on the parts you want to show livor mortis. Ask students what position the victim was laying in the hours following death.
Make each rat different! If you chose to stage the rat in the crime scene, some can show signs that they have been moved after death.
Rats may already be ‘wounded’ when they arrive to you depending on how they met their end. Use those wounds as part of the external examination.
Add red food coloring to the wounds you want to be ‘Perimortem’ (representing blood that came from the wound before death) and leave other wounds clean to demonstrate ‘Postmortem’ wounds.
Consider making some wounds too – add defensive wounds on the hands., or stab wounds with a small scalpel, or other ‘weapon’. Provide several possible murder weapons and have students determine which was used based on the shape of the wound.
Use a bee-bee gun (you will have to take it off campus first!) to give your rat bullet wounds. If you shoot at the right range and pump strength, the bullet will get lodged into the rat – great for your Medical Examiners to find!
If you don’t have access to a bee-bee gun, use a dissecting probe to punch a small hole in the rat, then take a small wad of aluminum foil (bullet) and push it through the hole.
For Gun Shot Residue, use a fine tip permanent black marker and make stippling to represent evidence of close range shots
Other Parts of the External Examination
Students can pry open the rat’s eyes, but they will not see much. If you want specific evidence there (hemorrhaging or cloudiness) consider providing a photo (digital or printed out) of a eye and have students use this photo for the eye evidence.
Students will need to identify the gender of their victim, as well as measure the weight and height, and general characteristics of their body.
Any distinguishing marks? Students can record fur pattern, or if you want to add some fun, create a little tattoo on the rat using permanent marker.
Forensic Science Autopsy Report
As your young Medical Examiners work, have them fill out some type of question sheet or Autopsy Report. The one I use is available at Teachers Pay Teachers.
The Autopsy Report covers both the external and internal examination – as well as Entomology, PMI, and a place where the Medical Examiner can put all the evidence together to come up with what may have happened at the crime scene.
This Autopsy Report is a great resource for teaching Autopsies even if your students are not going to dissect a rat. See the bottom of this post for some less gruesome ways to use Autopsies Reports in your Forensic Science classroom!
The Internal Examination
Show your students how Medical Examiners open a victim, and guide them on what organs to remove and weigh. I have my students work through this Autopsy interactive which allows them to ‘practice’ an internal examination before actually preforming it on the Rat.
Provide weigh scales for them to weigh their organs. Here is a database of different strains of rats, and how much each organ should weigh. Consider giving them access to this, or pulling an average from this data and providing it to them in a more simple format.
Inside the Rat
Give your rat signs of drowning by using a pipette to squirt dirty water into its mouth and lungs. Include algae or sand so it will be easy for your students to find and recognize when they open the lungs!
Consider creating a simple toxicology report for your students. Tell them that a particular substance was found in the blood – mix it up for different student groups!
X-rays can be found online and printed or provided digitally.
If you would rather keep it simple, just tell students that toxicology report came back negative for any substances, and there were no broken bones.
Most rats will have some food in their stomach, small or large intestine. This can be used to determine how long it had been since the ‘victim’s’ last meal before he was ‘murdered’!
Other Ways to Reinforce Forensic Autopsy Skills
You may have students who are very uncomfortable with doing a dissection. Time or budget constraints may also prevent a Forensic Science class from being able to go all out with a full Rat Autopsy.
That is okay! There are other ways to practice Forensic Autopsy skills with your students.
The Autopsy Report from Teachers Pay Teachers can still be used – no dead bodies needed!
- Have students make up a murder story and type it out with detail about age, gender, cause of death, time since death, location of the body, etc. Students then swap and read someone else’s story. As they do, they can fill out the Autopsy Report with the evidence they expect to find on the body considering how and when they died.
- Students make up a murder but instead of writing a story, have them fill out the Autopsy Report, and swap with another student. The second student then uses the report to form a story about how the murder happened.
- The teacher (or the students, and swap) can fill out the Autopsy Report but leave the last sections blank – the Post Mortem Interval, Type of Death and Cause of death. Students use the evidence in the report to complete these sections.
If you still want your students to be hands-on, check out this great idea for using Pickles as victims!
Looking for other Forensic Science teaching resources? Take a look at these from Science of Curiosity on TpT!