-a glass bottle, like a juice bottle, whose neck is a little smaller than a hard-boiled egg
-small or medium-sized hard-boiled eggs, peeled
-a long match or lighter
1. Decorate your bottle to look like a monster, with the mouth of the bottle on the mouth-end of the monster
2. Put one or two birthday candles in the wide end of a hard-boiled egg.
3. Light the candles and hold them under the inverted bottle to warm the air inside.
4. Hold your bottle upside down and put the candle end of the egg up into the bottle so it forms a seal. Continue to hold the egg until the candle goes out and the egg is “pushed” into the bottle by atmospheric pressure, which is the weight of the air pushing down on the egg.
The flame from the candle heats the air in the bottle. When the candle goes out from lack of oxygen, the remaining air in the bottle cools rapidly, decreasing the air pressure in the bottle and creating a partial vacuum. The outside air, whose atmospheric pressure is higher, pushes the egg into the bottle as it attempts to equalize the pressure inside of the bottle.
Plants love water as much as vampires love blood. Although they don’t have long thin fangs, they’ve developed a great system for pulling water up through their trunks and stems to their highest leaves using capillary action.
The kids and I demonstrated how to make them on Kare11 Sunrise news last week. Click here to watch.
Make a vegetable vampire and watch capillary action move colored water through the cabbage creature you created.
To make a leafy vampire, you’ll need:
-head of fresh napa cabbage
-2 large cups, jars or plasticware containers large enough to hold the base of ½ of your cabbage
-fruits and veggies to use as eyes and eyebrows on your monster
-rubber bands or string
First, fill your two containers ¾ of the way to the top with warm (not hot) water.
Add 10 or more drops of blue food coloring to one container and 10 or more drops of red food coloring to the other .
With a sharp knife, cut the cabbage in half vertically, from the bottom up, leaving the top 10cm or so intact, so the two pieces are still attached at the crown. If possible, try to cut down the middle of one of the big leaves.
Use rubber bands to secure the bottoms of each side of the cabbage and make a fresh cut at the bottom, a few cm up from the old cut.
Put one half of the base of your cabbage in the red water, and the other half in the blue water.
Decorate your two “vampires” with eyes and spooky eyebrows made from olives and peppers (or whatever you have in the refrigerator.) Secure the decorations with toothpick.
Keep an eye on your cabbage to see how much colored water it’s drinking. Your vegetable vampire will have to drink for 24-48 hours for the best results.
Plants survive by drawing nutrients dissolved in water up into their stems, stalks, trunks, branches and leaves.
Capillary action is the main force that allows the movement of water up into plants. In a narrow tube, on a surface that attracts water, the attraction between the surface and water, coupled with the attraction of the water molecules to each other, pulls water up. Plants are composed of huge numbers of tube-shaped cells that take advantage of these physical forces.
In this experiment, you can see colored water being taken up, via capillary action, into your cabbage.
Imagine how high the water in giant redwoods has to travel to reach the leaves at the top. In very tall trees, a process called transpiration helps the water overcome the forces of gravity. Here’s a transpiration experiment you can try at home.
Halloween Halloween brings out the kid in all of us, and there’s no better way to celebrate than with some ghoulish science experiments. Next week, I’ll be adding Vegetable Vampires and Zombie Candy to the lineup!
Here’s a list of our favorites. Just click on the name of the experiment to go to the instructions, see photos of what to do, and learn a little science. Most have links to videos or TV segments where I demonstrate how to do the experiments.
Shocking Machine Make an electrophorus and Leyden jar to shock your friends! Here’s how to do it. We demonstrated it on Kare11 last week!
Frankenworms Gummy worms soaked in baking soda and water come to “life” when you drop them into vinegar! Click here for directions and a video.
Goblin Goo (All you need is cornstarch and water. Here’s a video on how to make the goo. You can add a little food coloring to the water if you want, but it may stain your hands!)
Bag of Blood (If you have ziplock baggies, water, red food coloring and skewers, you can do this experiment!) Here’s the video.
Fizzy Balloon Monster Heads (After we made Goblin Goo, I demonstrated how to make Fizzy Balloon Monster heads. Click here to watch.)
Magic Potion (Bubbly, stinky Halloween fun: I made a short video on how to make magic potion. Click here to watch it.
Mad Scientist’s Green Slime (To see a TV segment where we made Mad Scientist’s Green Slime, click here!) Here’s another video.
Apple Mummies (Here’s a link to a TV segment where the kids and I demonstrated how to make Apple Mummies. Click here.)
Alien Monster Eggs (These make a great centerpiece for a Halloween party, when you’re done playing with them.) I demonstrated how to make them on Kare 11! Click here to watch the video.
Creepy Critter Slingshots Lob Marshmallow eyeballs and spiders at a pumpkin or another target in this fun physics experiment.
Got sugar? You can grow big, edible sugar crystals, commonly called “rock candy,” in your own kitchen. We thought they’d make a great science experiment to demonstrate at the Minnesota State Fair, where foods on a stick hold sway.
Like bricks in a wall, crystals are solids formed by repeating patterns of molecules. Instead of mortar, the atoms and molecules are connected by atomic bonds.
They can be big or small, but crystals made from the same atoms or molecules always form the same shape. Table sugar, or sucrose, is made up of a molecule composed of two sugars, glucose and fructose. The crystals formed by sucrose are hexagonal (six-sided) prisms, slanted at the ends.
To make rock candy on a stick, you’ll need: 5 cups white granulated sugar, 2 cups water, cake pop sticks or wooden skewers, and food coloring
- Dip one end of cake-pop sticks or wooden skewers in water and then roll them in granulated white sugar. The sugar should cover 2-3 inches of the stick. Let them dry completely. These are the seeds for the sugar crystal growth.
- Boil 2 cups water and 5 cups sugar until sugar is dissolved as much as possible. It should look like syrup. This is your supersaturated sugar solution.
- Let syrup sit until it is no longer hot and pour into glass containers. Add food coloring and stir.
- When colored syrup is completely cool, set the sugary end of the sugar-seeded cake pops or skewers into the syrup and let them sit for about a week.
5. Gently move the sticks around occasionally, so they don’t stick to the crystals in the bottom of the glass. If the glass container gets too full of crystals, pour the syrup into a new container and move your stick into the cleaner syrup to grow more crystals. When the rock candy is done, drain the excess syrup and let them dry. Enjoy!
The science behind the candy? A supersaturated solution is one that is forced to hold more atoms in water or another solute than it normally would. Supersaturated solutions can be made using heat or pressure. Crystals start to form when a supersaturated solutions encounters a “seed” atom or molecule, causing the other atoms to come out of the solution and attach to the seed. In this case, the seed molecules were the sucrose molecules we dried onto the sticks.
Biofuels are burnable energy sources produced by living organisms, like corn, algae, and even cows. Microorganisms and plants gather carbon from the atmosphere and incorporate it into the organic compounds that make up things like leaves, fruit, stems and wood. When animals eat plants and microbes, they store some of the carbon energy they’ve gobbled up as fat, like the milk fat used to make butter. Scientists call carbon stored in plants, microbes and animals “new” carbon. Old carbon is carbon tied up in fossil fuels like coal and oil, that’s been underground for millions of years.
Although butter isn’t usually burned as a fuel, a Pennsylvania farm show recently converted their thousand pound butter sculpture into 3 days-worth of power for a local farm, using a methane digester. The New York State Fair turned its butter sculptures into biodiesel fuel. At home, you can make a stick of butter into a candle to see for yourself how an animal product can be used as a fuel.
To make butter candles you’ll need a stick of butter, a toothpick or skewer, some cotton kitchen twine and scissors.
1. Cut the butter into the size candles you want. Place your candles on a fire-proof surface, like a metal plate.
2. Cut pieces of string slightly longer than the height of your candles.
3. Use a skewer or toothpick to poke a hole from the top of your candle to near the bottom.
4. Push your string into the hold using your skewer or toothpick. Leave 1/4 inch or so sticking out. This is your candle wick.
5. Rub a little butter onto the wick. Light your candle. It may take a few tries, but soon it should burn like a wax candle.
*As with all candles, butter candles should never be left unattended. Be sure to place your candles on a surface like a candle holder that cannot catch fire.
What happens? The lit cotton wick starts to burn and liquefies some of the butter fat. The wick then absorbs the melted butter and pulls it up,via capillary action, to the flame. The flame starts to burn the fat vapors rather than the wick, in a combustion reaction. This reaction produces heat, water vapor and carbon dioxide gas, putting the carbon is back in the atmosphere.
Since burning food isn’t an efficient use of energy or money (it takes lots of oil to raise and care for a cow,) scientists are coming up with ways to turn animal fats and byproducts that can’t be used as food into biofuels. Some inedible plant foods can be reused as well. For example, some cars can run on used cooking oil. Can you imagine how much oil a fast food restaurant throws away each week?
Although butter will never replace candle wax, butter candles are a good way to introduce the carbon cycle and get kids thinking about how new fuels and cleaner-burning fuel will impact the future of our planet.
To make the corn candle at the top of this post, we attached the butter candles to an ear of corn with broken off wooden skewers.
You’ll have a blast learning physics by making water rockets!
While NASA’s rockets use rocket fuel as their working mass, these rockets use water. As pressurized air forces the water out of your rocket, the rocket moves in the opposite direction, just like Newton’s Third Law says it will. “For every action, there is an equal and opposite reaction.”
Although these rockets lack fins, a payload and a nose cone, you can see from this NASA illustration that they’re very similar to real rockets. You can make a complicated launch pad like this, but we decided to make things easy.
For this experiment, you’ll need:
-an empty one or two liter bottle from a carbonated beverage
-a cork that has been cut in half and will fit in the mouth of your bottle (An adult should do this. I used a serrated knife.)
-a needle for inflating balls
-a bike or ball pump
-a cardboard box cut to hold the bottle at an angle pointing away from you. This is your launch pad.
Push the needle through the cork so that it pokes out of the other side. Use the hole from the corkscrew to make it easier.
Fill the bottle about 1/3 of the way full of water and insert the cork in the bottle.
Set the bottle in the cardboard box so that it’s pointing up, but away from you. See the photograph.
Attach the needle to the bike pump, stand behind the launch pad and start pumping air into the bottle. The air pressure will build in the bubble at the top of the rocket. When the pressure gets high enough, it will force the cork and water out of the bottle with lots of force, and as the water shoots down, the rocket will shoot up!
What happens if you add more water, or less water to your rocket?
Can you imagine riding a real rocket? Check out Astronaut Abby’s website to meet a girl who wants to ride a rocket some day and ask an astronaut on the International Space Station questions!
It only takes a spark to start a fire, and it only takes one atom to act as a seed for crystal formation. Under the right conditions, the atoms in alum will join together like puzzle pieces to form large crystals. I posted a few years ago about how to grow a large alum crystal, but this experiment is even more fun. It’s also easier for young kids, since it takes less small-motor coordination.
Alum is also called potassium aluminum sulfate. It’s used in pickling and in found in baking powder. You can grow beautiful alum crystals at home with a few jars of alum, water and any object you don’t mind covering with glue. We made fake geodes by breaking eggs in half and washing them out, but we also encrusted a grape stem and a plastic shark.
To do this experiment, you’ll need glue, 3/4 cup alum from the spice section of the grocery store (4 or 5 small jars should do it,) water and whatever you want to coat with crystals. It takes three days to complete.
On day one, paint glue on the objects you want to grow crystals on. If you’re making “geodes”, apply a thin layer of glue to the inside of an eggshell that’s been cut in half, washed out and dried. Then, sprinkle a little alum powder on the glue and let it dry overnight. We heavily coated our object with alum, but might have grown larger crystals if we’d used less. Each alum particle acts as a seed for crystal growth. The closer together they are, the less room your crystals will have to grow.
On day two, dissolve 3/4 cup alum in 2 cups of water by boiling. This step requires adult supervision. Make sure all the alum dissolves (it may still look a little cloudy) and let the solution cool. This is your supersaturated alum solution.
After about 30 minutes, when the solution is cool enough to be safely handled, gently immerse your object in the alum solution. For color, you can add a large squirt of food coloring. Let your project sit overnight to grow crystals.
On day three, gently remove your object from the alum solution and let it dry. How does it look? Draw it or take a picture to put in your science notebook!
Crystals are geometric networks of atoms. Imagine a three dimensional chain-link fence, and you’ll get the picture. Certain crystals will only grow in certain shapes. For example, diamonds are always cube-shaped when they form. Whether the atoms have joined to form a small diamond, or a large one, it will always be in the shape of a cube!
Some crystals, like alum, will form from supersaturated solutions, like the one you used in this experiment. A supersaturated solution is one that is forced to hold more atoms in water (or another solute) than it normally would. You can make these solutions using heat or pressure. Crystals can form when a supersaturated solutions encounters a “seed” atom or molecule, causing the other atoms to come out of the solution and attach to the seed.
What else could you try? Could you do the same experiment with salt, or sugar crystals? How do you think the color gets incorporated into the crystal? Do you think the food coloring disrupts the shape? Will larger crystals grow if you let your object sit in the solution longer?
You can read more about crystals and gems here.
I can’t get over how young my kids look in this post, which I first published a few years ago. This is a great science/art crossover project!
Summer has finally arrived, and a fantastic way to enjoy it is to take a nature walk. While you walk, watch for signs of spring and assemble your discoveries on your wrist with a nature walk bracelet. It’s always a good idea to bring a few bags along too- one for larger treasures (like pine cones) and one for trash. You can study nature and clean up the environment at the same time!
All you need is duct tape. Cut the tape so it fits comfortably around your wrist and tape it around like a bracelet, sticky side out. Take a walk in a park or down your own street and look for small leaves, acorns, flowers and other natural artifacts to adorn your wristlets. Be sure to watch for birds while you walk!
We wore our bracelets all afternoon and several people mistook them for real jewelry. My oldest daughter thought they looked even prettier as the leaves and flowers wilted and flattened out on the tape.
Have you ever wondered why it’s so hard to get ketchup flowing out of a bottle, or why no-drip paint doesn’t drip?
Ketchup, no drip paint, liquid soaps and shampoos are all part of a really amazing category of fluids known as “shearing liquids.” These fluids are pretty thick when they’re sitting still, but they get thinner or more “liquidy” as they flow, because movement decreases their viscosity, or thickness, making them more slippery.
Back in 1963, an engineer named Arthur Kaye noticed streams of liquid shooting from the surface below a stream of shearing liquid he was working with. This strange, short-lived phenomena became known as the Kaye effect.
With a chair, tape, some dish soap and a plastic ziplock bag, you can do your own Kaye effect experiment at home and watch soap jets shoot like ski jumpers from the very slippery shearing liquid soap pile below
-Tape a plastic ziplock bag to a chair with one corner or the bag pointed toward a plate underneath. The bag corner nearest the floor should be around 20 cm (about a foot) from the floor.
-Fill the bag with liquid soap or dish detergent. We added a few drops of food coloring to ours.
-Cut off the corner of the bag closest to the floor with scissors to make a tiny hole for the soap to flow through (1mm.) You may have to make it a little bigger, but you want a very thin, steady stream of soap flowing to the plate.
-Watch for jumping streams of soap. If it’s not working, try changing soap and adjusting bag hole size and bag height! What happens if you put the plate below at an angle?
To learn more about the Kaye effect and other cool physics stuff, visit Dr. Skyskulls’ website. He’s the physicist who told me about this experiment and helped me work out the protocol.
Here’s the video we made last weekend for KidScience app that shows you how to stand on a carton of raw eggs without breaking them:
Remember, Force is pressure per unit of area. In the video, you’ll see what happens when you try to stand on eggs in high heels and the force isn’t evenly distributed.