Egg in a Bottle

Today, we perform a feat of scientific ingenuity, and shove an egg into a bottle which is too small for it, without even touching the egg!


It's amazing! It's incredible! It has useful and important applications which will benefit society!

Uh...well, it's fun anyway.

You will need:
A hard-boiled egg
Very hot water
A bowl of very cold water
A glass bottle with an opening which is just slightly too small for your egg.  I used a Starbucks frappachino bottle with a large grade AA egg.
A bit of butter or oil

An adult!  Yes, because of the hot water, you must have an adult.  Hot water is very dangerous, and can give you burns--yes, burns, like fire--if it's not handled carefully.

Alrighty, let's get started!  First, empty out the bottle and grease the top and a little ways inside with the butter or oil, to make it super slippery for the egg.  Now, set the egg on top of the opening.  Have an adult tilt the bottle and hold it under the faucet, while you're running water as hot as possible.  Gasses expand when they're heated, so the air in the bottle will push out, popping the egg up ever-so-slightly to escape as the hot water heats it.

Once the air is good and hot, and lifting the egg up a teeny bit doesn't seem to let any air out, the adult can hand the bottle over to you.  Plunge it into the ice water.  If hot water heats up the air and makes it expand, what do you think cold water does?  It shrinks!  FUMP, the egg is pulled into the bottle!  This time, instead of wanting to push on the egg to let air escape, the cooling air shrinks and sucks on the egg.  It sucks and sucks, but the egg is a good seal--it doesn't let air past--so the only option is to suck the egg all the way in!

This project is good fun!  There are other things to do, too.  You can pop the egg back out again by having your adult hold the bottle upside-down under the hot water--the air expands again and pushes that sucker out!

If your goal is to baffle people, here's a very fun variation.  Instead of hard-boiling the egg, let the shell soften in vinegar for 12-24 hours.  The rest of the project is the same--but when the shell dries out, it hardens again! Now you have a normal, hard egg in a bottle with people wondering how on earth you got it in there!

Where do plants breathe?

Where do plants breathe--that's the question we tackle with today's project.  I hope you still have some Vaseline from the blob slide, because we'll be using it again in this investigation.

Plants do definitely breathe.  In fact, they breathe carbon dioxide and make oxygen--people and other animals breathe oxygen and make carbon dioxide.  We help each other that way.  If we had only plants on Earth forever, they would use up the carbon dioxide and die.  If we have only people and no plants, we'll use up the oxygen.

So they do breathe, but the question still isn't answered--where?  They don't have mouths or noses.  So how does the air get it?

To find out, you will need:
Three small, leafy potted plants
Petroleum jelly (Vaseline)

No adults required--although you might want permission to use the plants.

Air can't get through the petroleum jelly, so anywhere we put it on the plant definitely won't be able to breathe.  If we block a place with the jelly, and the plant does just fine and doesn't seem to care, then it must not breath there.  If we block a place with jelly and it drops down dead instantly then we've covered the only place it has for getting air.  The jelly is clear, so it won't block sunlight--only air.

On the first plant, carefully spread jelly on the undersides of all the leaves.  Label it "Plant 1."

On the second plant, spread the jelly on the tops of all the leaves.  This one will be "Plant 2."

Finally, on the third plant, we don't put any jelly on at all.  This is our control.  We compare the other two to this plant to see if the jelly made them better or worse, and by how much.

If you want, you can add more plant to the experiment and check other places--like the stems, for example.

Water all the plants normally and watch them over the next few days.  Which is doing the best?  Which is doing the worst?  What does that tell you about where plants get their air?  Do plants get all their air from either the top or bottom of the leaves, or is it a mixture?  If they get some air from both, do you think they get the same from each or is one side more important for breathing than the other?

Mini Monday: Blob slide

Hello girls, and welcome to the blob slide!  You might have noticed that in the hot summer, black asphalt is absolutely scorching, but light gray is better.  Today, we are going to harness that power, and bet on a race of penny blobs sliding down a tin can--based on our scientific knowledge, of course.

But first, materials!

You will need:
Petroleum jelly (Vaseline)
Two pennies
An empty tin can
A lamp without the lampshade
A black sharpie or black paint
Tin foil

You may want an adult for this one--the tin can can get very hot, very quickly!

First, color or paint half of the inside of the can black.

Next, make a little tin foil sunhat for your light bulb.  The open end of the can will sit on this.

Jaunty, no?

Next, but one blob of jelly on each penny.  Make the blobs as close to the same size as you possibly can.  Using the sticky jelly, stick the pennies on the outside of the can.  Put one penny on the side that's black inside, and one on the side that's not black.

Now, put the can on the light bulb hat and watch the blob slide begin!  Which side won?  Write down whether it was the black side or the light side, and hold at least three races.  Which side won the most?  Why do you think that was?

Black absorbs more heat than any other color, and white absorbs the least.  The black side of the can, then, should have gotten hotter than the light side, and melted the jelly on the penny faster.  Faster-melting jelly would make the black-penny slide down faster and win more often.  Did that happen in your experiment?  If not, what reasons can you think of that might have been more important than color, letting the light side win?  Maybe the light side was closer to the bulb, or had less jelly to melt.  When you figure out reasons for something unexpected in an experiment, that's real science!

Pinhole Projection

Laptop smiley-face mask pointed toward a pinhole in cardboard

Hello girls! Today we're going to project a smiley face onto the wall--using two pieces of cardboard, and some white light.

You'll need:
Two pieces of thin cardboard (like from cereal boxes), each larger than the screen you're using
A screen, like from a laptop
Scissors
Darkness (a room with no windows, or another room at nighttime)

That's it!  An adult could probably be pretty helpful on this project.

First, you create your mask. The mask is something that blocks light you don't want, and lets through light in the shape you do want.  We do this by cutting a big smiley face out of a piece of cardboard (but don't make it bigger than your screen).  Light can get through the parts you cut out, but not through the cardboard.  Thus, it is a mask.

Next, we create our pinhole.  Make a hole just a little too small for a pencil to fit through.

The pinhole is the only place light can get past the cardboard.  Check out the diagram below.  Light only travels in straight lines.  This means that in the bottom part of the picture (the trunk of this tree), light only travels to the pinhole if it's going upwards.  At the top of the picture (the leaves of the tree), light only gets through the pinhole if it's headed downwards.  They don't change directions as they shoot through the pinhole--so the picture ends up upside down!  This is pretty tricky stuff, so don't worry if it doesn't make perfect sense right now.

Now, let's see our projection in action!  Face your screen towards a blank white wall, only a few feet away.  Cover it with your smiley face mask.  Make sure the screen is as bright as it gets, and that you can make the room really dark.  Now, put the big sheet of cardboard with the pinhole in the middle right between the screen and the wall, and turn off the lights.  Your smiley is projected on the wall!  And it's upside down, of course!  Just flip the mask upside down and the outline on the wall will be perfect.  My smiley is very shy and dim, so I could not get a picture--this is a project to enjoy in person!  It's really very cool--I hope you enjoy it as much as I did.

Mini Monday: Feeling Sound

Hello girls!  Today's project is very simple, and it will allow you to actually feel sound with your hands.

Sound is actually air moving in patterns of more squished together--or compressed--and less squished together.  Compressed air moves out in a ring from where the sound started; when it hits our ears, it hits harder than other air and moves tiny things inside our ears.  Our ears detect this movement as a new sound.

Compressed air doesn't just hit our ears, of course; it hits everything in its way.  We don't usually feel it hitting us--but we can with that indispensable instrument of science, balloons!

You will need:
A balloon, filled so full any more might pop it

No adult supervision required!

Hold that balloon up to your mouth and talk.  Do you feel the balloon vibrating with your voice?  Try different sounds--low, high, ooooooos and yaaaaaaas.  Can you feel the different vibrations from air that's compressed in different ways?  You are feeling sound!

Maybe you think that's just your breath making the vibrations, and not really sound.  Well, try turning on a radio or stereo and holding the balloon near that.  Radios don't breath, but if it's loud enough, the balloon will still vibrate--and you will be holding sound in your very hands!

Simulating Erosion: Cracking Rocks

Hello girls!  Today I'm going to show you how to break rocks apart--you don't have to be strong, you just need to know your science!  This is on of the ways rocks break apart naturally.  Over many years, they can break into smaller and smaller pieces, until they're little grains of sand--this is called erosion.  How can this type of erosion happen?  With the weird properties of water.

Nearly everything shrinks when it is frozen, and gets better when it's melted--but not water.  Water expands when it freezes, and it doesn't let anything stop it, either.  We're going to let water seep into all the tiny holes in rocks--so tiny we can't always even see them--and then freeze it.  The water inside the rock freezes and expands, breaking the rock apart.

To do this, you'll need:
Rocks, of course.  We want to use sandstone--or if you don't have any, hunks of cement work too.  We want rocks with enough holes in them that this project doesn't take decades! Get many, many, rocks--only a few will turn out to be interesting!
Water in a big tub or bowl
Ziplock bags

No adult supervision required--although they might help you find good rocks!

First, gather your rocks.  Sandstone really does look like a lot of sand squished incredible close into a rock.  Next, soak them for an entire day in the tub of water.  You want the water to seep deeply into the rock before it freezes.  Dry them just enough so they're not dripping, zip them each in their own bag and stick them in a freezer.  It might take a while for the rocks to freeze all the way through, so give it a while--five hours or so.  You will have in your baggies rocks that have cracked and maybe even split apart entirely.  It just proves that brains triumph over brawn--even when it comes to tests of strength like breaking a rock into pieces!

Mini Monday: The Pepper Separator

Today, with the simplest of ingredients, we shall each become the Great Pepper Separator of our areas.   The effect of this is really quite surprising--I didn't expected it to be so fast!  You appear to just dip your finger into a bowl of water with pepper sprinkled on top, and the pepper shoots away from your finger!  Why?  What's the secret?

Well, our old friend surface tension!  We saw in the tin-foil soap boat project how surface tension is always stretched tight on top of the water, as if it were a spider web of ropes pulling in all directions--and when it's broken, it's like cutting the ropes there while they're still being pulled: everything flies away, just as if somebody cut the rope while you played tug-o'-war and made you fall backwards.

So when we sprinkle pepper on top of a bowl of water, everything is pulling, but it's balanced and none of the ropes are broken.  Sticking your finger in won't break the surface tension--but coating your finger in a little soap first, and then sticking it in, will!  Watch the pepper shoot away as the surface tension breaks, and the water it sat on flies away from your finger.  If you're sneaky, you can even make this into a "magic" trick--but you'll know the magic is in surface tension.