This is a super hard cipher to break. It’s encoded by taking pairs of letters and numbers from a matrix. There are three rules to follow.
Play Fair sounds really complicated, but that also makes it a tough code to crack! Watch the video and I’ll explain it all for you.
Cryptograms are solved by making good guesses and testing them to see if the results make sense. Through a process of trial and error, you can usually figure out the answer. Knowing some facts about the English language can help you to solve a simple substitution cipher. For example, did you know that an E is the most commonly-used letter in the English alphabet? It’s also the most commonly-used letter to end a word. Watch the video below to learn some more tips and tricks to get you on the right track to being an expert cryptogram solver!
Polybius was an ancient Greek who first figured out a way to substitute different two-digit numbers for each letter. In the Polybius cipher we’ll use a 5×5 square grid with the columns and rows numbered. Take a look at the video and I’ll show you how it works.
The Pig Pen cipher is of the most historically popular ciphers. It was used by Freemasons a century ago and also by Confederate soldiers during the Civil War. Since it’s so popular, it’s not a very good choice for top secret messages. Lots of people know how to use this one! It starts with shapes: tic-tac-toe grids and X shapes. I really like it because coded messages look like they’re written an entirely different language! Watch the video to learn how it works.
The Date Shift cipher is a much harder code to break than, for example, the more simple Shift cipher. This is because the shift number varies from letter to letter, and also because it’s polyalphabetic (this means that a single number can represent multiple letters). I’ll explain it all in the video.
Shift ciphers were used by Julius Caesar in Roman times. The key is a number which tells you how many letters you’ll shift the alphabet. These are fairly simple to encode and decode. However, you have to be extra careful when encoding because mistakes can throw off the decoding process. Watch the video to see why it’s important to double check your work!
In this video, I demonstrate a Twisted Path Cipher. It uses a matrix and a path in order to encode your message. The shape of the path you create within the matrix of a Twisted Path Cipher determines how difficult it will be to break the code. Watch the video to learn exactly how it works.
Cryptography is the writing and decoding of secret messages, called ciphers. Now for governments these secret ciphers are a matter of national security. They hire special cryptanalysts who work on these ciphers using cryptanalysis. The secret is, solving substitution ciphers can be pretty entertaining! Ciphers are published daily in newspapers everywhere. If you practice encoding and decoding ciphers, you too can become a really great cryptanalyst.
In this video, I’ll show you how to use the Rail Fence Cipher. Before you start, say this three times fast: cryptanalysts use cryptanalysis to crack ciphers!
Secret codes and ciphers are so much fun to learn about and create! This particular secret code machine is a simpler model of the original that was so complex, it took a brilliant mathematician, Alan Turing, to devise the techniques which cracked the code.
In order to create this paper machine, you’ll need the templates which you can find here. Before you print and cut them out, watch the first part of the video, because chances are, you’re going to have to re-size it so it will fit your container.
If you look carefully at color images inside of books with a magnifying glass or a microscope, you’ll find there are only four colors that make up all the different colors you see. We’re going to learn how to separate the color that makes up different color markers, which work the same was as the colored printed images in books.
If you have access to a microscope, then this lab is fun and easy to do. If you’re in the market for a microscope, you can view our microscope recommendations here. If you’ve got a microscope but just haven’t used it for awhile (or never), then look over the experiments here first to get you started. Cloth fibers, wool, human hair, salt, and sugar all look really different under a microscope. It’s especially fun to mix up salt and sugar first, and then look at it under the scope to see if you can tell the difference.
This project is for advanced students. Make sure you’ve completed the Police Siren project first!
This is a really cool one. You’re actually going to build a miniature radio station. You can broadcast your voice or music to a regular FM radio. It just has a very short range (about 100 feet, or 30 meters).
This experiment is for advanced students. There are many different elements inside of a star. But they are so far away that we can’t get close enough to study them… or can we? By studying the special light signature (called “spectral lines”) astronomers can figure out not only which element, but also the approximate temperature and density of the element within the star, in addition to getting an idea of what the magnetic fields look like, which tells us about stellar wing and what the planets might be doing around the star, or if there might be another companion star.
Spectroscopy is a very complicated science, so let’s get started by actually doing it, and we’ll figure out what’s going on along the way.
If you find a white powder at the scene of a crime, how can you tell if it’s flour or something more dangerous? A detective uses a chemical lab to determine what the substance is. One of the things that scientists look for is pH, which is a measure of how acidic or basic the powder is based on either a color change or how much a substance reacts with baking soda.
Did you know that when you talk inside a house, the windows vibrate very slightly from your voice? If you stand outside the house and aim a laser beam at the window, you can pick up the vibrations in the window and actually hear the conversation inside the house.
First, I’ll show you how to build your own space-age laser communicator, then you can work on your spy device. The first thing we’re going to do is take the music from your iPOD (or stereo, or MP3 player) and transmit it on a laser beam to a detector on the other side. The detector has a earphone attached, so someone else can listen to the music from your laser. Weird, huh?
Can you spot a fake $10 from the real thing? It’s getting harder these days, but you can still do it using a microscope.
US dollar bills are make of a mix of cotton and linen, which is why they don’t fall apart when you leave them in your pants pocket and they go through the water. They also have trace amounts of iron embedded in them, so they flex slightly toward a strong magnet. Can you find the owl on the dollar bill?
Burglar alarms not only protect your stuff, they put the intruder into a panic while they attempt to disarm the triggered noisemaker. Our burglar alarms are basically switches which utilize the circuitry from Basic Circuits and clever tricks in conductivity.
Note: there are FOUR videos on this page, and FIVE experiments!
Every crime scene has a silent witness called physical evidence, and fingerprints are one kind of physical evidence. The patterns of ridges on both the finger and toe are unique to each person; no two are alike, which allows fingerprinting to help identify who did what, when, and where. Your fingerprint pattern will never change throughout your entire lifetime, which makes it a handy tool for identification. The main patterns are arch, loop, and whorl.
Fingerprints are friction ridges made up of a single row of pores in your skin. When your finger touches a surface, oil and sweat transfer from your finger to the surface and leave an impression of the ridge pattern from your finger.
Here’s a list of the supplies you’ll need to complete most of the basic experiments in this series:
Note that the more advanced experiments, including the laser alarms, trip wire, pressure sensors, laser maze, and laser transmitters have their own individual materials listed with each experiment. Please refer to each experiment for a full and complete itemized material list with order links.
As a kid, I absolutely loved Encyclopedia Brown and Sherlock Holmes. What I really loved most about them was the science behind how they caught the bad guy… and now I’m going to share with you the basics of crime scene investigation in this section on forensic science.
Forensic science is a lot like engineering… it’s a place where you get to use stuff you’ve learned in other fields and apply it to the real world. With forensics, you get to use biology when you identify blood, DNA and diatoms; chemistry when you’re identifying unknown powders and poisons; physics when you’re looking at shattered glass, bullets, and explosions; and earth science with you’re looking at soil evidence.
The basic principle that forensics is based on is that someone either brought something to the crime scene or left something behind, which is called trace evidence. Trace because it’s usually really small, like a fiber of clothing, a hair, bits from a shoe, paint chips, wood splinters, or latent (invisible) fingerprints.
There’s a lot we’re going to cover! We’re going to several different fingerprinting methods, including how to lift fingerprints so you can study them as well as how to make artificial fingerprints using stuff from around the house. You’ll also learn about chromotography, which is how to separate black ink into its different colors so you can find the pen that actually wrote the mysterious letter.
We’re also going to learn how to do fiber flame tests to be able to help you identify which fibers are which so you can match it with what the suspect is wearing. Chemical analysis is also really important, and you’ll learn how to tell which powder is which using a matrix technique. We’ll also look at counterfeit money by making microscopes, fake documents in different wavelengths of light, and learn how handwriting tells you a lot about a person and how they think and feel.
In addition to collecting and analyzing evidence, we’re also going to learn how to secretly listen to conversations inside the house from the front yard, how to make laser burglar alarms to help you catch the bad guy, make rear-view spy glasses that let you see what’s going on behind you, write in different types of invisible ink, a wireless FM transmitter so you can transmit your voice to your allies without using walkie talkies, and learn how to make your own laser maze by building the home-made transistor detectors (these are the ones we use at Science Camp in the Laser Maze)!
There are over 20 videos to take you step by step into the world of evidence, analysis, investigation, and decoding mysteries! Are you ready?
By controlling how and when a circuit is triggered, you can easily turn a simple circuit into a burglar alarm – something that alerts you when something happens. By sensing light, movement, weight, liquids, even electric fields, you can trigger LEDs to light and buzzers to sound. Your room will never be the same.
Switches control the flow of electricity through a circuit. There are different kinds of switches. NC (normally closed) switches keep the current flowing until you engage the switch. The SPST and DPDT switches are NO (normally open) switches.
The pressure sensor we’re building is small, and it requires a fair amount of pressure to activate. Pressure is force (like weight) over a given area (like a footprint). If you weighed 200 pounds, and your footprint averaged 10” long and 2” wide, you’d exert about 5 psi (pounds per square inch) per foot.
However, if you walked around on stilts indeed of feet, and the ‘footprint’ of each stilt averaged 1” on each side, you’d now exert 100 psi per foot. Why such a difference?
The secret is in the area of the footprint. In our example, your foot is about 20 square inches, but the area of each stilt was only 1 square inch. Since you haven’t changed your weight, you’re still pushing down with 200 pounds, only in the second case, you’re pressing the same weight into a much smaller spot… and hence the pressure applied to the smaller area shoots up by a factor of 20.
So how do we use pressure in this experiment? When you squeeze the foam, the light bulb lights up! It’s ideal for under a doormat or carpet rug where lots of weight will trigger it.
This method of decoding messages uses special ink that is invisible until something is done to make them appear on the paper. There are hundreds of formulas to make these special inks and some formulas even have multiple ways to develop the ink. Some recipes involve special chemicals, but many invisible inks can be made using materials that you have in your home. Watch the video and I’ll share a few recipes and teach you more about this method.
