Crime Scene Lab
A forensics class runs its crime scene in a shoebox with ketchup, or buys a class pack of licenses every year. Crime Scene Lab is a virtual crime scene that runs in the browser: a student photographs the room before touching anything, sets the markers, bags the evidence the right way, powders the glass and lifts the prints, swabs the drops, and takes the note to the lab. At the bench they classify and compare the fingerprints against the suspects' cards and make the call an examiner makes, turn each bloodstain's shape into its angle of impact and run the strings back to where the drops came from, run the note's ink beside every pen on a chromatography strip, type the blood, and put the fiber under the microscope. Then they write the case: claims in their own words, each with the evidence it stands on, and a line on what the evidence cannot say. The teacher opens the saved case and grades it. The culprit is different for every student unless the teacher fixes one.
Using this with a class? Make a free class and add your students yourself: each gets a username and password, with no email or Google account needed. Or give them one join code. Using Google Classroom? Post the link there; with a free class, the link also puts each student in your class, so you see their work. mytekDev is also available from the Google Workspace Marketplace, so your school's Google admin can install it for everyone.A first lesson: One period for the scene and the fingerprint station. One period for bloodstains, with the angle of impact figured by hand. Three periods for the whole case, handed in with the claims and the log of what went wrong at the scene. The Stage tab lets a student tell a new story, and the app lays the evidence to match and says whether the scene still closes.
Set up a free class Share to Google ClassroomWhat a student actually does
The scene is a school hallway at night, a room the student can turn and zoom: a trophy case with a broken pane and the cups still in it, glass on the floor, a trail of dark drops to the side door under a glowing exit sign, a note on the desk, lockers, tape across the main door. It is dark until the first photo, and the pointer is a flashlight. Press a place and the camera flies up to it; the tools work on the room seen close. The tools lie along the bottom the way a scene kit opens: camera, markers, scale, gloves, tweezers, powder, tape, swab, measure. The camera takes the whole room first, then a surface, then a close-up with the scale in the shot, which is the only photo the lab can measure from. A marker goes beside a thing before it is picked up. A shard picked up before its photo is logged as having no photo in place, for good. A swab put in a plastic bag spoils before the lab opens it. A print powdered with the gloves off carries one that matches nobody. The strip under the scene counts the photos, the bags, the lifts and the mistakes on the record, and never hides the last number.
The Lab has six stations. Prints: name the pattern of a lift, mark its ridge endings and bifurcations, find the same ones on a suspect's card, and call it identification, exclusion or inconclusive. Spatter: measure a stain's width and length with a caliper, build the formula for the angle out of chips (middle school reads it off a chart of shapes), and drag strings along the drops to find where they came from and how high the hand was. Ink: stand the note's ink and each suspect's pen on a chromatography strip, pick water or alcohol, watch the solvent climb, read each band's distance and the front, and work out the Rf. Impressions: measure the shoe print in the dust against each suspect's soles. Blood: type a swab with three sera and read the clumping. Fibers: the thread from the broken edge under the microscope beside each jacket.
The Case tab asks four questions: who was in the room, what happened in what order, what the evidence does not tell you, and what you would test next. Each answer is a claim in the student's words with evidence chips attached from the scene and the lab, and a chip carries its weakness with it: no scale, two points, a bare hand on the item, spoiled. The student says who the evidence points at and hands it in. If the teacher allows, the true story opens beside the claims with every call marked right or wrong. The printed case has the plan, the sketch, the chain of custody, every station's numbers and the claims. The answer key prints only from the teacher's setup.
The lift is the suspect's real finger seen through the tape, smudged where the brush went again. The student marks the ridge features on the lift, finds the same ones on the card, and counts the pairs. The app never says a number of points makes a match, because examiners do not.
What they are learning while they work
Nothing here is presented as a lesson. This is what the activity is made of.
| What the student does | What it is |
|---|---|
| Picks up a shard before photographing it, and reads the log line | Document before you touch. A thing moved without a record of where it lay has lost most of what it could say. The chain of custody is the paper trail that follows every item from the scene to the lab. |
| Counts the deltas on a lift and picks loop or whorl | Fingerprint classification. About 65 percent of prints are loops and about 30 percent whorls; a loop has one delta and a whorl at least two. The high school level uses the eight classes of the standard scheme. |
| Marks eleven pairs of ridge features and still calls it inconclusive | ACE-V and the examiner's three calls. Analysis, comparison, evaluation, verification. There is no fixed number of points that makes a match; a partial, smudged lift may never give enough, and the app says so. |
| Measures a stain 5 by 15 mm and builds asin(width / length) | Angle of impact. A drop that falls straight down is nearly round; as the angle drops, the stain elongates and its tail points the way it was going. The sine of the angle is width over length. |
| Drags three strings and watches them cross by the case | Area of convergence and origin. Lines through the long axes of the stains cross where the drops came from. With the angles and the distance, the height they fell from is an estimate, and the app calls it one. |
| Runs the note beside four pens in water and gets nothing, then in alcohol | Chromatography and Rf. An ink is a mixture of dyes that separate as the solvent climbs. Rf is the band's distance over the solvent's, a constant only while the paper and the solvent stay the same. A match says the inks are the same kind, never which pen. |
| Types the swab as B negative and rules out two suspects | Class evidence and individual evidence. A blood type, a fiber or a shoe tread can rule a person out; it can never point at one person. Only the prints in this case do that, and the Build tab's verdict says which evidence closes a scene. |
How to tell whether it landed
Ask, and let them show you. A student who has understood it can answer these without help.
- You picked up the long shard before photographing it. What did the scene lose, and what does the chip on your claim say about it?
- Lift 4 has one delta and a core. What class is it, and which of Avery's fingers could it be?
- You called lift 4 an identification with three pairs. Why does the app call three points a weak call, and what would an examiner want?
- The stain is 5 mm wide and 15 mm long. What is the angle, and what does the tail tell you?
- The note's ink runs like Avery's pen and like Quinn's. Which one wrote it?
- The blood is O positive and so is Morgan's. Does that put Morgan in the room?
Use it in your subject
Not a technology class? Then the app is how students show what they learned in your unit. More projects for every subject.
Forensic science
The standard course by unit: the crime scene and the chain of custody, fingerprints, bloodstain pattern analysis, questioned documents, impressions, serology and trace. One case runs through all of them, and the Case is the unit's assessment.
Biology and chemistry
Chromatography as separating a mixture, with Rf measured and compared; ABO and Rh typing on a slide; the fiber under the microscope. Each station is the lab the textbook describes, with the numbers the student's own.
Math
The angle of impact is the inverse sine of a ratio, built from chips and run on every stain the student measures. The height of the origin is a tangent. The sketch is two distances from fixed points.
English and argument
The Case is claim, evidence, reasoning: a sentence in the student's words, the chips it stands on, and a line on what the evidence cannot say. It prints for grading with the chain of custody beside it.
Middle school science
The middle school level: three pattern classes, the angle read off a chart of shapes, three questions in the Case, and the Prints station alone if the teacher turns the rest off.
Practical notes
- AgesHigh school forensics electives are the home ground, grades 9 to 12, with the eight pattern classes, the angle by formula and the height of the origin. The middle school level fits grades 6 to 8 with three classes and a chart of shapes.
- TimeOne period for the scene and the Prints station. One period for Spatter. Three periods for the whole case with the hand-in. The Build tab is a fourth period for a class that builds scenes for each other.
- EquipmentA computer or Chromebook with a modern browser. Nothing to install. A printer if you want the case, the sketch and the answer key on paper.
- CostFree. The app has no paid tier.
- PrepWork the scene yourself once, about twenty minutes: photograph, mark, powder and lift, send the lift, compare it at the Prints station. Print the answer key from Setup. Decide whether the culprit is fixed for the class or different per student.
- In a groupOpen Setup in the app's header: the level, which stations are on, whether the culprit is the same for the whole class or different for each student, gloves kept on, whether the true story shows after hand-in, and your own questions for the Case. Hand the project out as the starter and every student's copy carries it.
For co-ops, microschools, and classrooms
Set the case up once in Setup and hand the project out as the starter; the setup travels with it. With a free class each student's case saves to their projects and prints with the claims, the chain of custody and the log line of what went wrong at the scene. The answer key for the seed prints from your copy. The Stage tab lets a student write a scene and share it: whoever remixes the project gets that scene to solve, and the app has already checked that it closes.
Common questions
Is there a body?
No. The case is a break-in: a broken trophy case, a missing cup, a cut hand, a note. Nobody is hurt and nothing in the room is a weapon. The blood is a dozen small drops on a floor, drawn flat, and the Spatter station can be turned off in Setup.
Is it free for teachers?
Yes. The app runs in the browser with no paid tier, the demo needs no account, and a free account adds saving, the class starter and the printed case.
Does it work on Chromebooks?
Yes. The room is a small 3D scene with a handful of lights and no textures to download, and it runs on a school Chromebook; where a browser has no WebGL the app shows the same hallway as a drawing. The stations are drawings and tables.
Do all the students get the same answer?
No, unless you want them to. The culprit is chosen by each project's seed, so two students beside each other have different prints on the glass and a different pen on the note. Setup can fix one culprit for the whole class.
Can I grade it?
Yes. Hand in prints the case: the plan with the sketch, every item's chain of custody, each station's numbers and calls, the claims with their evidence and its weaknesses, and one line of what went wrong at the scene. The answer key prints from Setup and never appears in a student's copy.
Are the fingerprints real?
No. Every print is generated by the app from a ridge-flow field, so the app knows where every ridge ending and bifurcation is on every card and can check a student's pairs. No real person's print is in it.
Is the science right?
Every line the app says is checked against a published source, and the teaching notes say which. Where classroom handouts overreach, the app is careful: no number of points makes a match, a chromatography match says the inks are the same kind and not which pen, and a blood type rules out and never identifies. If you find a line wrong, use the contact form.
Can students write their own scene?
Yes, two ways. The Build tab is the full builder: say who did it, write the note and what each suspect says, and put the evidence where it lies by pressing a spot in the room: drops at an angle, a fan of drops from a hand, a smear, a shoe print, prints on the glass, a fiber on the broken edge. It says whether the evidence closes on the culprit and why. The Stage tab is the quick way: one sentence with orange words that the app lays out. Either way the saved project carries the scene for whoever remixes it, and both tabs stay shut for a student solving the case until hand-in. Setup can lock them for good.
Is it safe for middle school?
Yes. The middle school level in Setup uses three pattern classes, reads the angle off a chart of shapes, and asks three questions in the Case. The case has no victim, and anything a student types goes through the platform's word filter.
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Where to go next
Lesson plans
3 ready-to-teach class periods with a teacher plan, a student worksheet, an exit ticket with answers, and the standards it meets.
Start with Crime Scene Lab
Trying it costs nothing and takes about five minutes. An account is what makes the work last.
Crime Scene Lab is one of the making apps on the platform. The case, the people, the prints and the inks in it are invented, and every fact it states is sourced in its teaching notes.
Page last reviewed October 2026.
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