Eggshell Geode Crystals

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This project comes to us from Melissa Howard who is a Mom, Blogger, and photographer. This project nicely demonstrates how real-life geodes are formed in igneous and sedimentary rock. It also demonstrates super-saturated solutions and shows a nice variety of crystal shapes and formations.

YOU WILL NEED:

• clean eggshells
• water
• a variety of soluble solids: table salt, rock salt, sugar, baking soda, Epsom salts, sea salt, borax, or cream of tartar
• small heat proof containers (coffee cups work well)
• spoons
• food coloring
• egg cartons and wax paper or mini-muffin tins

WHAT TO DO:

1. Crack the eggs for this project as close to the narrow end as possible. This preserves more egg to use as a container for the solution.
2. Clean the eggshells using hot water. The hot water cooks the lining and allows you to pull the skin (egg membrane) out of the inside of the egg using your fingers. Make sure to remove all the egg membrane, if any membrane stays inside the shell it is possible that your eggshell will grow mold and your crystals will turn black.
3. Use an egg carton lined with waxed paper or mini-muffin tins to hold the eggs upright.
4. Use a saucepan to heat the water to boiling. .
5. Pour half a cup to a cup of water into your heatproof container. If you poured half a cup of water into the container, add about a ¼ cup of solid to the water. Stir it until it dissolves. Likewise if you used a cup of water, add about ½ a cup of solid to the water. You wanted to add about half again the volume of the water as a solid to the mixture. When the initial amount of solid is dissolved continue adding small amounts of the solid until the water is super-saturated. Super-saturated simply means the water has absorbed all it is able to absorb and any solid you add will not dissolve.
6. Add food coloring.
7. Carefully pour your solution into the eggshell, filling it as full as possible without over-flowing it or causing it to tip.

Find a safe place to put your shells while the water evaporates. Crystals will form inside the eggshells as the water evaporates.

HOW DOES IT WORK?
Dissolving the crystals in hot water created what is called a “super-saturated solution.” This basically means that the salts took advantage of the energy of the hot water to help them dissolve until there was no more space between molecules in the solution. As the solution cooled, the water lost its energy and the crystals are forced from the solution to become a solid again. Since this happens slowly along with the evaporation, the crystals have time to grow larger than they were when the experiment started. Natural geodes in rock are form in much the same way as mineralized water seeps into air pockets in rock. This is also how rock candy crystals are formed.

You can visit Melissa’s great blog and see more pictures HERE.

Oobleck – The Corn Starch And Water Experiment

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This may just be the easiest, messiest, and most fun science activity I know. It is a classic, and I have gotten several requests recently to post directions. You should know that if you try this activity and  you are not smiling and messy with corn starch goo at the end, then you are definitely doing something wrong. Also keep in mind that this is not just about fun, there is some pretty amazing science going on here.

You will need:

• Cornstarch (a 16 oz. box is good for every 2-3 participants – but more is always better)
• Water
• Food coloring (we always say it’s optional, but it does make it more fun – don’t use too much or you could end up with colored hands)
• A large bowl
• A camera – you’re probably going to want to take pictures.

Everyone should roll up their sleeves and prepare for some gooey fun.

1. This is easy. Pour the cornstarch into the bowl. Don’t rush to add water – take time to feel the cornstarch. Cornstarch does not feel like any other powder. It has a texture that can be compared to that of whipped cream. The grains of cornstarch are so small that they will fill into grooves of your fingerprints and make the prints stand out.
2. After you’ve taken-in the feel of the powder, it is time to add water. (You should add the food coloring to your water before adding it to the powder.) There are no exact formulas regarding how much water to add, but it will end up being about 1/2 cup (120 ml) of water per cup (235 ml) of cornstarch. The secret is to add the water slowly and mix as you add it. Don’t be shy here – dig in with your hands and really mix it up. This is usually when you notice that this is not your average liquid. Add enough water so that the mixture slowly flows on its own when mixed. The best test is to reach in and grab a handful of the mixture and see if you can roll it into a ball between your hands – if you stop rolling it and it “melts” between to fingers – success!

We’ll get the the science soon, for now just dig in and explore. Notice that the goo does not splash (or even move) if you hit it quickly. Squeeze it hard and see what happens. How long can you get the strands of goo to drip? What happens if you let the goo sit on the table for a minute and then try to pick it up? How does it feel? Hows does it move? Try bouncing a ball on the surface of the cornstarch. You get the idea – explore!

30 minutes later…

So now goo is everywhere and you’re thinking you should probably start cleaning. Actual clean up of the goo is a snap. A bucket of warm water will quickly get it off your hands. It will brush off of clothes when it dries, and it is easily cleaned off surfaces with a wet rag. Important: Make sure you do not dump the goo down the drain – it can get caught in the drain trap and take the joy out of your day of science. Dump it in the trash, or even mix it into soil in the garden.

Cornstarch grains under the microscope

Now for the science…
Our cornstarch goo (sometimes referred to as “oobleck” from the Dr. Suess book) is what scientists call a “Non-Newtonian” liquid. Basically, Sir Issac Newton stated individual liquids flow at consistent, predictable rates. As you likely discovered, cornstarch goo does NOT follow those rules – it can act almost like a solid, and them flow like a liquid. Technically speaking, the goo is a SUSPENSION, meaning that the grains of starch are not dissolved, they are just suspended and spread out in the water. If you let the goo sit for an while, the cornstarch would settle to the bottom of the bowl.

So why does this concoction act the way it does? Most of it has to do with pressure. The size, shape, and makeup of the cornstarch grains causes the cornstarch to “lock-up” and hold its shape when pressure is applied to it. People have filled small pools with oobleck and they are able to walk across the surface of it (as long as they move quickly.) As soon as they stop walking, they begin to sink.

I hope you get to try this out. Let us know how your day with non-newtonian liquids went. Comment here, or, even better, send us pictures to comment@sciencebob.com . Have fun exploring!

-Science Bob

Growing Bacteria For Science Fairs

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Testing for bacteria (germs) can be a great idea for a science fair experiment since there are so many possibilities for science questions, and because carrying out the experiment is pretty easy using widely available bacteria growing kits. Besides, who doesn’t like checking out bacteria and fungus?

All good science experiments start with a question – this is what you want to find out by experimenting. Here are a few example questions to get you started using the scientific method for growing bacteria:

• Is a dogs mouth cleaner than a humans mouth?
• Who has the cleanest mouth in the class?
• Do antibacterial soaps really kill bacteria?
• Which door handle in the school has the most bacteria?
• Does toothpaste kill bacteria in your mouth?
• Do dark socks create more bacteria in a shoe than white socks.
• Do hand sanitizers work to kill bacteria?
• What location in the school contains the most bacteria?
• Is there more bacteria in tap water, bottled spring water, rain water, or pond water?

Step 1 – Ask A Question: Let’s imaging that you want to answer the question, “Which door handle in the school has the most germs?”

Step 2 – Research: You can’t just jump in and start experimenting. It’s important to do a little research. Ask the school nurse which door handle he or she thinks the most germs (bacteria) are. Observe and chart which door handles get the most use, survey friends and family to get opinions and write down the results. All this information will help you narrow down which door handles are the most likely to contain germs – and which ones you should choose to use in your experiment.

Step 3 – Make a Hypothesis: This is when you make a prediction based on your research. This is not an “I think…” prediction, it is a statement that will either be proven true or false based on experimenting. An example would be, “The handle to the nurse’s room contains the most bacteria.”

Step 4 – Experiment: This particular science experiment requires a simple bacteria testing kit. You would choose several door handles that you think might contain the most bacteria. These door handles are considered the Independent Variable in your experiment because each handle is independent and you control which ones are chosen. In a typical kit you would touch a separate cotton swab to each door handle, and then touch it to the bacteria growing Petri dish so that you would have one dish for each handle. Take good notes that would include when you collected each sample and where you collected the sample, and be sure to label everything well in any experiment.

Step 5- Collect Data: In this experiment, bacteria will start to grow in the Petri dish over the next few days, and you may be surprised by just how much gross bacteria is lurking in your school. Take good notes each day and determine which dish has the most bacteria growing in it.

Step 6 – Make Your Conclusion: This is when you decide if your hypothesis is correct. If your hypothesis was, “The handle to the nurse’s room contains the most bacteria,” your experiment will show if your hypothesis was right. It is not bad at all if your hypothesis is incorrect, what is important is that you answered your question from step 1. Now pat yourself on the back for your fine scientific discovery using the Scientific Method.

CLICK HERE for information about Bacteria Growing Kits.

Halloween Science Experiments & Ideas!

Need ideas for your Halloween party, or just some all-around Halloween fun? Here’s a few great ideas to get you started.

GLOWING DRINKABLE BEVERAGES
Did you know that tonic water will glow under a blacklight? We didn’t either. The quinine in the tonic water glows a very cool looking blue color that we really like. If you’re not crazy about the taste of tonic water,  try making ice cubes using the tonic water and then add them to a glass of Sprite or another light colored citrus drink. Switch on the blacklight and you have the perfect Halloween beverage. After a few minutes the entire drink will start to glow. (see photo)

MAKE SOME HALLOWEEN SLIME
Slime and Halloween go together like, well, slime and Halloween. Here’s 2 ways to add a little slime to your October.
Do it yourself slime - If you’ve got a little glue and some powdered borax, you can easily mix up some slime by following the instructions HERE.

Slime Kits - If you want to make LOTS of slime as an activity, or if you have trouble finding Borax, a kit may be the way to go. We have just the slime kits you are looking for. You can find out more by clicking HERE.

EERIE GREEN PUMPKINS
All your neighbors will have Jack-O-Lanterns that glow orange, but you will impress them with a Jack-O-Lantern that glows green! Best of all, the green glow is simple and safer than traditional candles. Purchase one or two large glowing light-sticks per pumpkin at a party store or hardware store. (We like green, but there are many colors to experiment with) Activate the light stick and simply drop them into the pumpkin, or, to conceal the glow sticks, attach them to the inside of the pumpkin lid by unbending large paperclips to secure them. Place your pumpkin outside on Halloween night and admire the “Oooos” and “Ahhhhs” of Trick-Or-Treaters.

MAKE A HAUNTED, SCREAMING CUP
If you think haunted houses are scary, wait until to hear…haunted drinkware! First, check out our Chicken In A Cup experiment, but instead of pulling along the string in short bursts to sound like a chicken (it really does, trust us) pull in one continuous motion. The result is an eerie screaming cup! The only thing better than than trying the screaming cup yourself, is trying the screaming  cup with LOTS of your friends all at once.  Parents especially seem to enjoy that. The  instructions can be found HERE.

BUBBLING POTIONS AND JARS
Every mad scientist needs some bubbling potions. While dry ice may be the ultimate bubbling potion, the effect tends to be short-lived, and dry ice can be dangerous around younger Halloween party goers. The solution is a simple aquarium pump. Purchase an inexpensive aquarium pump and some tubing at your local pet store along with a line splitter (if you want more than one bubbling potion.) Set up the pump to send bubbles into various large food jars through the tubes. Add some food coloring, plastic bugs or fake body parts, and you’ve got the sights and sounds of a mad scientists lab that will last all night. For added drama, light up the jars from below using flashlights. You can also create floating eyeballs by drawing an iris and pupil onto ping-pong balls with permanent markers. Make a few that will float around by drilling two very small holes in the ping-pong balls and allowing them to fill with water until they sink. For an added glowing blacklight effect add our Glow-Bright Concentrate.

GHOST BUBBLE SPHERE
If you’ve got some dry ice, (available at some grocery stores and most ice companies) why not gather Halloween party-goers and try your hand at making a large dry ice ghost bubble? You will need:

• Medium size bowl with a rim
• Small bowl
• Liquid soap
• 20 inch by 2 inch strip of absorbent cloth (cotton or cheese-cloth work well)
• Dry Ice

Fill each bowl halfway with water. In the small bowl, add a good squirt of liquid soap (we like Dawn Concentrate) and stir it up. Dip the cloth into the soapy water to get it wet. Get the rim of the larger bowl wet with water and add the dry ice . Admire the sights and sounds of bubbling dry ice. Now the tricky part, pull the cloth strip so that it is taught and pass it across the entire rim of the medium bowl to create a soap bubble “skin” over the bowl. It may take several tries. Once you get it, the bubble will expand as gas is released and it will rise to create your own ghost bubble sphere.  After the soap gets into the water with the dry ice, you are treated to soap bubbles filled with dry ice mist! CAUTION: Never touch dry ice! It’s -109° F (-78° C) That’s really, really cold.

CLICK HERE for instructions to make a static powered dancing ghost.

THE SCREAMING QUARTER EXPERIMENT

If you have some dry ice from the Ghost Bubble Sphere left over, you might want to try this fun little demonstration. Dry ice is the solid form of carbon dioxide. As it sublimates, (turns back into a gas) the carbon dioxide gas escapes around the quarter causing the quarter to vibrate and make a rather spooky shrill along with occasional humorous sounds. Always wear gloves when performing this demonstration.

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FOR  HALLOWEEN RELATED ITEMS
FROM OUR NEW STORE, CLICK HERE.

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Fun With a Blacklight

As we get ready to open up our new on-line science store later this month, we have had a lot of fun testing products. We recently received a box full of fluorescent minerals which we will make available in small kits. In the name of quality control, we decided to set them up and see how well they fluores under your typical, run of the mill, party store blacklight. As you can see, the effect was beautiful.

Minerals under regular light
Minerals under our Ultraviolet (blacklight)

Try This:
A blacklight is a great item to have in  your science collection. Here is a great nightime science activity that you can try with your kids. Get an inexpensive battery powered blacklight, They are available on our web site or at many party stores or hardware stores. Go into a dark room and switch the UV light on. Now start looking around. Open drawers like toy drawers, clothes drawers, and closets. Many surprising objects are likely to start glowing. White clothing, “neon” colored paper, glow-in-the-dark-objects, even tonic water will glow under a blacklight.Try writing notes using a highlighter marker under the blacklight.

How does it work?
The light waves from an ultraviolet light (blacklight) excite the molecules of certain materials enabling them to reflect back light. In the case of fluorescent minerals, the light that is reflected back is often an entirely different color than the original mineral. Minerals such as calcite, wernerite, and willemite emit a bright colorful glow. Depending on where you live, you might be able to go out at night and find some fluorescent minerals of your own. Did you know scorpions glow under ultraviolet light? Get out and see what you can explore with a blacklight!

Our mineral sets are now available! To learn more, click HERE.

7 Year Old Explores Bubble Gum Science

7 year old Sarah of Tennessee wondered if all bubble gum was created equal and which of the many brands of bubble gum in the candy aisle would giver her the largest bubble? All this wondering led to a science fair entry that won first place.

Sarah made great use of The Scientific Method to answer her sugary suspicions. Sarah’s hypothesis was, “Gum that is harder, stickier, and has more sugar will make bigger bubbles than gum that is softer, not sticky, and less sugary.” She carefully tested 6 popular brands of bubble gum being sure to chew them all the same and keep careful notes.  She measured carefully (with help from Mom) and charted her results. After the sugar rush subsided, she reviewed her data and she was a bit surprised by her conclusion. So what is the most bubbly of the bubble gums? Try it out yourself and find out. Besides any time you can mix candy and science, it’s a good thing. Congratulations on your experiment Sarah!

You can follow their blog by clicking HERE.

All posts are reprinted with permission of the author, and they maintain all applicable copyrights. To use any material in this post, please contact them.

Homeschoolers discover the science of SLIME!

Lara runs a homeschooling blog from her home in Arkansas. One day, she gathered her kids and all the materials to make slime but she did not tell them what they would be creating. Using a familiar recipe, the boys were soon measuring, mixing, stretching, and yes, even learning about types of matter and polymers. Here’s Lara’s proportions for her large batch of slime. (See link below for smaller batches and to get some information about the science of polymers)

• 1 8-ounce (240 ml) bottle of glue
• 2 cups of (480 ml) warm water, divided
• food coloring
• 1 1/2 (8 ml) teaspoons Borax powder
• bowls for mixing

Pour the whole bottle of glue into a big bowl then fill the empty bottle with 1 cup of warm water and add that to the glue. Stir it up until it thins out.Then add several drops of food coloring and mix that in.In a separate bowl mix the Borax and the second cup of warm water until the Borax dissolves.Stirring CONSTANTLY, slowly pour the Borax into the bowl of glue. Stir and stir and stir until it forms into a goopy, slimy, mass. Remember to store it in an airtight container or it will dry out.

CLICK HERE FOR MORE DIRECTIONS AND THE SCIENCE OF SLIME

Visit Lara’s homeschooling  blog

Your Levitating Orb Videos

A few students that have tried the levitating orb, have made videos for YouTube. Here are a few that we have found:

We want to add you to this page! Simply make a video of your levitating orb experiment, post it on YouTube, and send us the link at comment@sciencebob.com, and we’ll post it here.

New Zealand students study density with Blobs In a Bottle.

Ian Stewart, a teacher at the St. Andrews School in Hamilton, New Zealand was looking for a way to make learning about density a hands-on experience. Then he stumbled across our Blobs In a Bottle lava lamp experiment (link below) at sciencebob.com. The students got to work creating their own blobs in bottles as they explored molecular polarity and liquid density. They used different shaped bottles to see if it changed the effect, and they added different colors as well. Ian reports the experiment was a success and the students were able to bring their experiment home to keep the discovery process going.

SO WHY DON”T OIL & WATER MIX?
The Blobs in a Bottle experiment is an excellent way to teach about the sometimes confusing concept of density in liquids. Density, in this experiment, is demonstrated when the oil floats above the water. This is not because the water is “heavier” than the oil. In fact, all the oil in the bottle likely weighs more than all the water in the bottle, but a glass of of water would weigh more than an equal sized glass of oil. This is because there is more matter (sometimes more easily referred to as “stuff”) packed into the equal amount of water. Another way to think about it would be to compare a brick made of clay, and one the exact same size made out of styrofoam or wood. Even though they are the same size, the styrofoam is less dense. The clay brick has more “stuff” packed into the same amount of space – it is more dense! See, I told you it can get confusing.

Density, however is NOT why the oil and water do not mix. No, that is due to a little thing called molecular polarity. Molecular polarity basically means that water molecules are attracted to other water molecules. They get along fine, and can loosely bond together (drops.) This is similar to magnets that are attracted to each other. Oil molecules are attracted to other oil molecules, they get along fine as well. But the structures of the two molecules do not allow them to bond together. Instead, they are like magnet that repel away from each other. Of course, there’s a lot more fancy scientific language to describe density and molecular polarity, but maybe now you’ll at least look at that vinegrette salad dessing in a whole new way.

Blobs In A Bottle Experiment

Teaching about insects with a Floating Paperclip.

Ellen Kahue, a teacher in South Carolina cleverly used our Floating Paperclip experiment (link below) to teach how water strider insects are able to move across the surface of  water without sinking. Understanding surface tension can be a bit tricky, but once you see a paperclip “float” on water, the concept begins to make sense.  Students were challenged to get the paperclip to float on their own. If you’ve ever tried this, you know it can be very difficult…unless you know the secret.

Ellen used the lesson to show how water striders take advantage of surface tension. These insects spread their weight out on their legs which allows them to stay supported, and easily move across  on the surface of the water.

Click here to see the secret of the The Floating Paperclip

Click here to visit Ellen Kahue’s website and blog

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