Wednesday, May 18, 2011
Monday, May 16, 2011
First, mark an “x” on the index card (big enough to see!). About two inches to the left of the “x” we’re going to put a dot. Now is where the stick comes in. A ruler stick works great, but if you don’t have one you can get creative (I used a broom). Now hold the card about an arm’s length away from you, facing you so that you can see the dot and the x. Hold the stick so one end is up against you, resting on your cheek (Be careful! You don’t want to poke yourself in the eye!) and the other end is pointing away from you, out like a telescope. If you are looking down the stick, it should look something like this.
Wednesday, May 11, 2011
Bloomin' billowing blue! That was weird! I just created my own color clock reaction--a chemical reaction that waits, waits, waits--then bam turns blue just like that!
You will definitely need an adult for this one! For one thing, iodine stains--if an adult was helping, it's not your fault if something gets ruined. Also, glasses or goggles (ones for snow, water, or construction work just as well as science ones) are a good idea to protect your eyes.
Hydrogen peroxide, on the other hand, has the opposite reaction: it causes two I- to bond back into an I2.
Meanwhile, left to their own reaction, I- and I2 would react and bond into three iodine atoms together, I3-. But, the Vitamin C reaction is very fast, so at first there aren't any I2 around long enough to make I3-. Vitamin C turns them into I- before they get a chance to become I3-! Once all the Vitamin C is all used up, though, there is still enough hydrogen peroxide to make plenty of I2, and that makes it possible to make I3-. This can get confusing, I know, but we're at the color part. Vitamin C runs out quite suddenly, and that means I3- can be made quite suddenly, too. I3- and starch (whether it's from laundry or corn) form a complex together which is dark blue. And that's where the sudden blue bloom comes from! Whew, that was a lot of chemistry in a row. And the effect is spectacular!
Once you're through with the blue, it's perfectly safe to wash it down the drain. Wash out anything that touched iodine really, really well--it's poisonous if you eat it!
Monday, May 9, 2011
You will need:
Maple or corn syrup
Liquid dish soap
A clear glass
No adult supervision required--but keep this away from anybody that might try to drink it, like little brothers or sisters!
If you like, you can use food coloring on the boring-colored liquids (like milk, water, and rubbing alcohol) to make your glass a rainbow!
Pour each liquid in one at a time, and very slowly. Pour them in the same order that they're listed above, and keep anything from touching the walls of the glass as your pour. The exception is rubbing alcohol--since it's last, you can touch the sides of the glass as you pour. Be extra careful with rubbing alcohol--if it goes through the vegetable oil as you pour, it will mix with the water layer and stay there! (That happened to me). Which is the densest? Which is the least dense? Pour very carefully--and enjoy your colorful layered result, courtesy of density!
|Liquid layers after rubbing alcohol mixed with water|
Thursday, May 5, 2011
We've done an experiment with a pendulum before--so you might already know that a pendulum is a hanging weight, and it swings back and forth for a long time when it gets a little push. What you might not realize is that how far the pendulum swings depends on the length of its string. In today's project, we're going to made a bunch of pendulums and hang them all right next to each other--and each pendulum will have a different string length. When they all swing together, they make really cool patterns!
You will need:
As many weights as you want (but I'd say have at least 5 or 6 to see the patterns). I recommend using fishing weights that already have a nice place to tie your string.
Thin fishing line
A long bar to hang the pendulums on--I used one in a playground
A long flat thing, like a plank of wood, binder, or piece of cardboard
No adult supervision required!
Cut a piece of fishing line at a length you like--about 3 feet works well--and loop it over the bar. Tie the ends onto one of your weights. Next, cut a new piece of string that is longer than the first one--and measure exactly how much longer. Each new string will be exactly this much longer than the string before it. (You don't need a ruler to do this--I picked a piece of bark about 2 inches long, and made each new string as long as the one before it, plus the length of my bark.) If you have lots of weights, you can make each string only a little bit longer--say, half an inch. If you only have a few weights, you'll be able to see the cool patterns better if you make them about 2-3 inches longer.
Once you've cut your strings, loop them over the bar and tie the ends to the a weight, just like the first one. Line the weights up in height order (it doesn't matter if you go longest to shortest or shortest to longest).
They should look something like this diagram when you're done.
|Blue string looped around a black bar, and tied to green weights|
Want to see what this looks like when a professional does it? Here are two mesmerizing examples:
Monday, May 2, 2011
Hello girls! Last Thursday we learned how to lift latent fingerprints to identify who's been where. That is certainly an important skill for anyone doing detective work to know. However, there are many small tricks that a detective might need to use. Today's Mini Monday is a collection of them!
Makeshift magnifying glass:
A magnifying glass is curved: when light hits it, instead of just passing through the glass like a window, the light is refracted, or bent. The bent light makes the object look bigger to your eye, and that makes it easier to see very small details--details that could be very important. But you don't need to carry a magnifying glass around with you--or even own one! The bottoms of many glass cups are also curved. You know what that means--you have yourself a makeshift magnifying glass! Peer down into the glass and slide it over things, like a page out of a book, to see if it's magnified (and how much). Different glasses will magnify things differently--so try them out!
Sometimes, detectives need to get inside locked doors--maybe someone behind them needs help, and can't open the door from the inside because they're passed out, or only a baby. Picking locks like the one on your front door is difficult, and takes serious training--it's not something I know how to do. But some locks, like those on most bathroom doors, are easy to pick and every girl should know how. The locks you can pick have small, round holes instead of a place to put a key. You can pick this lock by sticking something skinny, long and hard straight back into the hole and pushing. Things that work well are Allen wrenches, bobby pins, or a straightened-out hook of a wire hanger (the last one is my favorite). It is important to hold the lock-pick perfectly straight as you slide it in; if it doesn't work at first, just pull it out and try again. I recommend having somebody inside the bathroom when you try this, or locking it while it's open--that way if you have trouble you won't be locked out of the bathroom for hours! Oh, and be sure to check that nobody's using it first, of course.
How to tell if something has been added to a copied document:
Detectives don't only catch thieves who grab things and run: they also catch thieves who cheat and trick to steal. One of the ways thieves cheat people is by adding things to contracts after they've been signed, and pretending the extra writing was there all along. If somebody used computer programs to do this, you'll probably need equally fancy computers programs to catch it. But one really common way of altering documents can be caught with your own eyes--if you know where to look. Often, criminals simply write extra things on their copy of the contract, and then copy it again to make it look like it was always there. So how do you catch this? Every time a document is copied by a photocopier, it loses some of its fidelity--that is, it is a little less clear and crisp. It can get noise, small black and white speckles, on it. Writing looks more jagged, with tiny little sharp edges, instead of smooth writing like with a pen. So here's the trick: when a perfidious bad guy has a copy of something, writes on it and copies it again, the first writing has been copied twice and the added writing has only been copied once. The real writing will be twice as jagged and noisy as the fake writing added later. So if some writing looks a lot newer and smoother than other writing, your suspicions should be instantly raised. Try this by writing your own note, copying it (most libraries make copies for only about ten cents), writing something new on the copy, and copying that. See the difference? It may be very small, but you can learn how to see it, just like a detective would.
Should you trust an alibi?
If a crime took place and you are interviewing a suspect, chances are they'll have an alibi--something else they say they were doing, or somewhere else they say they were, when the crime happened. The problem is, people telling the truth and liars all want you to believe their alibi. So how can your spot a lie? There are two good ways. First, their story might have lots of holes in it. This requires real detective work--check in on every tiny detail, because if they're lying, they might have missed something. Perhaps the suspect said they went to a diner the day of the crime--but if you go to the diner and check, you might find out there was a kitchen fire during that time, and everybody had to stand in the parking lot for ten minutes while it was put out. That's something they would know if they'd actually been there!
But there is another way to spot a lie, too. Really professional criminals won't make many mistakes like that--they are sure to check these things themselves, the same way you would. They will have absolutely spotless alibis that you can't find even the tiniest thing wrong with--and that's the giveaway. If they're really innocent, the day of the crime was just a day in their life--and life isn't spotless. Real people, in real life, do not remember every detail of a random day in their life perfectly. They do not remember the exact time they did everything, and they do not remember what everybody they met that day was wearing--you get the idea. If someone remembers everything perfectly and nothing can be questioned, they probably thought it up beforehand. Don't forget about them and don't let it go.
Now you have a full set of skills to investigate with. You can find and preserve fingerprints, make a magnifying glass nearly anywhere, pick locks, spot fraud on a contract, and spot fake alibis by clumsy crooks and professionals alike. Use your new skills well. Investigate with honor, and never give up. Even the cleverest, richest, slipperiest malefactor can always be brought to justice, if one dogged detective refuses to give up.