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Forensics, Detectives, and CSI Lesson

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I am a Christian. I was an 8th-grade American History teacher. I am currently a freelance writer, public speaker, & homeschooling mom of 9.


This is a hands-on lesson plan on detectives. Analyze fingerprints and hair samples, take mug shots, solve a real crime, and more! My lessons are geared toward 3rd-4th grade level children and their siblings. These are lessons I created to do with a weekly homeschool co-op. We meet each week for 2 1/2 hours and have 16 children between the ages of 1-13. Use this fun lesson with your class, family, after school program, camp, or co-op!

Nate the Great detective hat

Nate the Great detective hat

Detectives Introduction

1) Stretch & pray. Discuss Matthew 7:7.

2) Briefly discuss what a detective is.

3) Make detective hats by printing off the detective hat pattern on p. 4 of If desired, have children wear their detective hats.

YOU WILL NEED: 1 copy of the detective hat pattern and band (pre-cut) per child and staplers or tape

4) Read "Lu & Clancy's Crime Science" (Lu & Clancy) by Louise Dickson or "Nate the Great" by Marjorie Weinman Sharmat. Afterward ask children what clues the detective used to solve the crime.



5) Discuss what fingerprints are. Get a stamp pad and fingerprint each finger on one hand. Compare each fingerprint. What patterns do you see? Try to count the lines on one fingerprint. Use a magnifying glass if available.

YOU WILL NEED: inkpads, magnifying glasses, baby wipes (for cleaning off fingers, and copies of the first page of "The Fingerprint Worksheet" from

Lifting figerprints

Lifting figerprints

6) Have the children rub their fingers on their faces (where there are plenty of oils.) Have them touch a window, table, glass dish, or other item. Give each pair of children a small paintbrush and a small cup of cocoa powder (NOT hot chocolate mix). Have them lightly brush on the powder where they touched the window. If needed, they can gently blow off the excess cocoa powder. Have them place a piece of clear scotch tape on top of the fingerprint and then gently pull it from the window. Stick it onto an index card. Tell them that this is how detectives get the fingerprints from a crime scene. After a detective has fingerprints from a crime scene, they may have a suspect for that crime. They will take the suspects fingerprints and compare them to the one's they have from the scene. In order to safely say the fingerprints came from the same person, they must have 12 similarities. Isn't it amazing that each of our fingerprints are different from anyone else's? God made each of us unique. Psalm 139:14a says, "I will praise You, for I am fearfully and wonderfully made."

YOU WILL NEED: index cards, small make-up brushes or paintbrushes (the softer the bristles the better), small cups, cocoa powder or graphite powder, & scotch tape

(If you are not limited by time) Pull one of the index cards from the group and have the children try to match the index card fingerprint to the fingerprints just taken in the previous activity.

Viewing hair under a microscope

Viewing hair under a microscope

Hair Analysis

7) Briefly discuss hair analysis. Have each child use a hairbrush or comb they brought with them to brush their hair and take out a strand of their hair, or just have them each yank out 2 strands of their hair. Have them give one of their hair strands to the person on their right and keep one hair for themselves. Compare the two pieces of hair. Have each child label a snack size plastic bag with their name and place their hair sample in the bag. Ask, "What are some things you notice? Is the color the same? Is one thicker than the other? Is one curlier or straighter than the other?" If you have access to a microscope, let the children compare strands of hair from 2 different people. Place the hair samples next to the fingerprint samples. If you have a microscope, allow children to view different hair and fiber samples (include dog fur and cloth thread).

YOU WILL NEED: snack or sandwich-sized Ziploc bags, sharpie markers, and a microscope

Posing for mug shots

Posing for mug shots

Scroll to Continue

Artists Sketches and Mug Shots

8) Quickly discuss artist sketches and mug shots. Take mug shots of each of the children (both a front & side profile). Divide children into more than one group and have multiple mothers take pictures to save time if desired.

YOU WILL NEED: a digital camera & sign for the kids to hold in front of them for the mug shot


Committing a Crime

9) TEACHER/PARENT 1: Have someone else place a plate of cookies or other treats on the table for children to have when they return. While children go outside, inconspicuously stay inside "to clean up." Turn over some chairs near the cookie platter to make it obvious that a "crime" had been committed. Pour some milk in a drinking glass and drink it, or just press your fingers all over the drinking glass and lay it next to the cookie tray. Lay a large hair sample next to cookie tray. Place the paper with your shoe print on it on the floor so that it looks like it was just left there and you stepped on it. Take a bite out of one of the cookies and put it on the table. Crumble up another one and sprinkle the crumbs around. Put the rest of the cookies and the plate in your bag. Do this all as quickly as possible so that you will hopefully not get noticed. Quietly join the rest of the group outside.

YOU WILL NEED: a plate of cookies or other treats, a bag or purse large enough to hold a plate of cookies, a piece of paper that has your shoe print on it (Do this by stepping in dirt or paint and then stepping on the piece of paper. You will need to do this while wearing the same shoes you’ll be wearing at co-op, or do it while barefoot.), some of your hair (from your hairbrush), and a drinking glass with a small amount of milk in it


Shoe Prints

10) Shoe prints: Take children outside. Explain how shoe or footprints can show not only how big a suspect's foot is and but also how fast the person was walking/running, the type of shoe they were wearing, and sometimes how heavy the person is (by how deep the impression is). Stand next to a sandy or muddy spot. (We dug up some dirt in our yard and then sprayed it with a hose.) Let some of the children walk through the mud, run through the mud, and leap through the mud. Notice how the shoe prints look different. Notice also how the bottoms of the shoes each look different too. (If you are not limited by time) have 1 child close their eyes (the detective) and another person go through the muddy area (the criminal). Have the child detective try to determine who just went through the mud. Make sure that a few children have muddy shoes.

YOU WILL NEED: baby wipes or towels just in case we need to clean up

Forensics, Footprints, and Body Proportions Activity

Forensics, Footprints, and Body Proportions Activity

Footprints and Body Proportions

11) Footprints can tell us even more about a suspect. Did you know that detectives can use a footprint to tell how tall someone is? They know a few rules that most bodies follow. They are rules about proportions, or how large one body part is compared to another. Most people are about 6-7 times as tall as the length of their foot! If forensic (detective) scientists find a footprint in the dirt, they will have some idea of how tall that person was. Divide children into groups of 3-4 children. Help the children to cut a piece of yarn the length of their foot. Place the yarn on the ground and have the child step in it without his/her shoe on. Cut the string to be just the size of their foot. After everyone has that string cut, have them use their foot-length string to measure the inside of their forearms and the length of their faces, from their hair to their chin. It should be the same as their foot size! Next help them cut a strand of yarn to be the length of their bodies, from the top of their head to the ground. Help them use the foot-length string to “measure” the body-length string. Is is 6-7 times the length of your body?

YOU WILL NEED: scissors and yarn

K-9 Police Detective

K-9 Police Detective

Police Detective

12) Option A: If possible have a police detective stop by your school or house. We called our local sheriff's office a couple weeks ahead of time and they happily agreed to send out a K-9 detective (the police officer and his dog). They stayed for about 15 minutes and showed the children how they train their dog. Then the officer answered questions. This was by far the favorite activity of the day! If your police department would prefer that you come by their office, you could arrange to head over there after your lesson/co-op. (Just to forewarn you, our local sheriff's office said it would be better for younger children to not go to their office because they have some items that are related to illegal substances along with other items that we may not want our children to see. Your police/sheriff office may be different. )


Target Practice

12) Option B: (If you are not able to have a detective come by your house)Target practice: Set up targets outside and have children use nerf-type guns to try to knock down targets. Have them practice with both their right and left hand.

YOU WILL NEED: nerf-type guns and targets (like aluminum cans)


Solve the Crime, Snack, & Review

13) When you return inside, a teacher/parent needs to cry out that a crime has been committed. Have the children try to determine who the thief is by using what they learned today.

14) Eat the recovered snack item that had been stolen.

YOU WILL NEED: napkins and small cups for water

15) Review what we learned today. Ask the children questions such as: What did you learn about how police officers train and use dogs? How do detectives use fingerprints to solve crimes? What are the 3 main fingerprint patterns? (arch, loop, or whorl) How do detectives lift fingerprints? What can forensic scientists learn about someone from their hair sample? What can detectives learn about a suspect from their footprint or footprints? What is a mug shot? What was your favorite activity from today?

Fun Detective Picture Books

Also look for "Who Pushed Humpty Dumpty? : And Other Notorious Nursery Tale Mysteries" by David Levinthal, "Inspector Hopper" by Doug Cushman, "Henry and Mudge and the Sneaky Crackers" by Cynthia Rylant, Detective LaRue: Letters from the Investigation" by Mark Teague, and "Piggins" by Jane Yolen.

Great Detective Chapter Books or Books for Older Children

An excellent additional chapter book is "The Story of Scotland Yard" (A World Landmark book) by Laurence Victor Thompson. If you have older children, they might also enjoy the Graphic Forensic Science, which is written in graphic novel (comic book style) format. Some of the titles include "Crime Scene Investigators" by Rob Shone, "Solving Crimes with Trace Evidence" by Gary Jeffrey, and "Detective Work with Ballistics" by David West.

Material List for the Lesson

-a detective hat (If you don’t have one, print one off from p. 4 at and color it, cut it out, and staple it. If you don’t want to color it, you can simply print it off on colored paper.)
-magnifying glass (optional)
-pen or pencil
-ink pads (1 per family)
-copy of "The Fingerprint Worksheet" found on p. 17 of
-paintbrush or make-up brush – the softer the bristles the better (1 per family)
-scotch tape (1 per family)
-scissors (1 per family)
-yarn or string (1 per family)
-sharpie marker (1 per family)

-book: "Lu & Clancy's Crime Science" (Lu & Clancy) by Louise Dickson or "Nate the Great" by Marjorie Weinman Sharmat
-baby wipes (for cleaning off fingers)
-index cards, small cups, and cocoa powder or graphite powder
-snack or sandwich-sized Ziploc bags and at least one microscope (optional)
-signs for the kids to hold in front of them for the mug shots
-a plate of cookies or other treats, a bag or purse large enough to hold a plate of cookies, a piece of paper that has your shoe print on it (Do this by stepping in dirt or paint and then stepping on the piece of paper. You will need to do this while wearing the same shoes you’ll be wearing at co-op, or do it while barefoot.), some of your hair (from your hairbrush), and a drinking glass with a small amount of milk in it
-baby wipes or towels just in case we need to clean up
-scissors and yarn
-napkins and small cups for water

Great YouTube Video Clips on Forensics

Also look for "Bill Nye the Science Guy: Forensics."

Dragonfly TV Kids Do Science - Forensics

Just for Fun: Goofy: How to Be a Detective


Looking for My Other Lesson Plans?

Over the years I have posted over 30 science and social-studies based unit studies, compromised of more than 140 lessons. For each lesson I have included activities (with photos), our favorite books and YouTube video clips, lapbook links, and other resources. I posted links to all of my unit studies and lessons at Fun, FREE Hands-on Unit Studies .

Konos Volume II

Konos Volume II

Konos Curriculum

Would you like to teach this way every day?

Konos Curriculum

I use Konos Curriculum as a springboard from which to plan my lessons. It's a wonderful curriculum and was created by moms with active children!

Konos Home School Mentor

If you're new to homeschooling or in need of some fresh guidance, I highly recommend Konos' program! Watch videos on-line of what to do each day and how to teach it in this great hands-on format!

© 2011 Shannon

Comments, Questions, & Ideas - I LOVE getting feedback from you! Please leave a note to let me know you dropped by!

Shannon (author) from Florida on August 19, 2012:

@BarbRad: Yes, they were fun to read about! My children loved getting to pretend like they were detectives.

Barbara Radisavljevic from Paso Robles, CA on August 18, 2012:

My son would have loved this. I loved to read about Pinkerton's detectives.

Shannon (author) from Florida on July 09, 2012:

@Cyberwing: Thank you!

Cyberwing on July 09, 2012:

Wonderful idea. Should try this. Nice lens

Wedding Mom on May 20, 2012:

Great lens.

kathywiehl on December 15, 2011:

This is awesome! I'm great at the book learning part of homeschooling, but coming up with creative ideas is difficult for me. Thanks so much!

SnoopyGirl1 on December 06, 2011:

This is awesome I will have to try it with my kids. I am beginning Konos with them this spring.

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