Don’t worry to much if you don’t have whole milk or heavy cream. Nearly any milk will work and you can substitute half-and-half for the cream. Ideally you want ingredients with a high fat content because these will create a creamy texture when cooled. Remember that we’re just experimenting here, so try what you have on hand!

Ingredients

• 1/2 cup milk (Whole or 2% work best)
• 1/2 cup heavy cream (optional)
• 1/2 teaspoon vanilla
• 1 tablespoon sugar
• 4 cups crushed ice
• 4 tablespoons salt
• 2 quart size plastic bags
• 1 gallon size plastic freezer bag
• a hand towel or gloves to keep fingers from freezing as well

Basic Directions

Begin with mixing the milk, vanilla and sugar together in one of the quart size bags. If you want, you can mix this in a bowl first so that you get all the sugar dissolved. Seal the bag tightly, you want to try to get as much of the air out of the bag as you can. Too much air left inside may force the bag open during the mixing stage.

Place this bag inside the other quart size bag, again leaving as little air inside as possible and sealing well. By double-bagging, the risk of salt and ice leaking into the ice cream is minimized.

Put the two bags inside the gallon size bag and fill the gallon sized bag with ice, then sprinkle salt on top. Again, squeeze out as much air as possible and then seal the bag. Wrap the bag in the towel or put your gloves on, and shake and massage the bag, making sure the ice surrounds the creamy mixture. Five to eight minutes should be enough time to allow the mixture to freeze into ice cream.

When you are all done carefully open the bags and extract your ice cream. Enjoy!

If you’d like to experiment a bit more you can try substituting a mixture of heavy cream and your choice of milk. Mix up a few different batches and compare the texture of ice cream. Which to you think will have a smoother texture?

We suggest using freezer bags because they are thicker and less likely to develop small holes, allowing the bags to leak. You can get away with using regular plastic bags for the smaller quart sizes, because you are double-bagging. If you plan to do this indoors, we strongly recommend using gallon size freezer bags.

What does the salt do?

Salt forces the ice surrounding the bag of ingredients to melt. This “brine” solution or liquid that forms in the gallon bag absorbs the heat from the ice cream mix and gradually lowers the temperature of the mix until it begins to freeze.

If there were no salt added to the ice, it would melt at 32 degrees Fahrenheit and eventually the ice water and mix would come to equilibrium at 32 degrees. The ice cream mix, however, does not begin to freeze until its temperature falls below 27 degrees. Therefore, in order to freeze the mix, we need to add salt to the ice to lower the freezing temperature.

With 4 tablespoons of salt mixed with our ice, the brine temperature should remain constant at around 8 to 12 degrees Fahrenheit. This will give the rapid cooling and freezing that is essential to making smooth creamy ice cream.

Start by cleaning out the bottle and filling it with about 2 inches of water. Now pour in the vegetable oil to nearly the top. In order to color your lava, you will need to add several drops of food coloring. Notice that the food coloring does not mix or color the oil as the drops sink.

Materials:

• Plastic bottle (any size)
• Vegetable Oil
• Water
• Effervescing antacid tablet
• Food Coloring

What to do:

1. Fill the plastic bottle with 2 inches of water.
2. Fill the rest of the way with vegetable oil.
3. Put in 5 or 6 drops of food coloring.
4. Drop in an effervescing antacid tablet and you just made your very own lava lamp.
5. Try putting a flashlight under the bottle see what the lava lamp looks like now!

What is the Science?
Oil will not mix with water it is an example of a hydrophobic molecule. The term hydrophobic literally means water fearing from the Greek language hydros “water” and phobos “fear”. Food coloring is a hydrophilic molecule. The term hydrophilic literally means water loving from the Greek language hydros “water” and philic “friendship”. The food coloring has the ability to mix or transiently bond with the water (H2O) through hydrogen bonding. When you place the effervescing antacid tablet into the bottle it will dissolve in the water and form bubbles of carbon dioxide gas. The gas rises and takes some of the colored water along with it to the surface of the oil. When all of the gas has escaped out of the top of the bottle the water droplet falls back to the bottom of the bottle.

What you need:

• 1 cup hot water
• 1.5 tsp. Borax (non-toxic/available by laundry detergents)
• 2 cups clear glue
• 2 cups warm water
• 1 tsp. liquid watercolor

What to do:

1. Mix 1 cup hot water and 1.5 tsp. of Borax until dissolved. Set aside.
2. Mix 2 cups of clear glue and 2 cups of warm water together in a plastic bowl.
3. Using a metal spoon, slowly pour Borax mixture into the glue mixture while stirring quickly. Stir until the mixture leaves the side of the bowl. Slime will be sticky. Knead the mixture until it is no longer sticky. The more you work with it the easier it will become.

What’s the science?
Slime is an excellent example of a polymer. The word polymer comes from the Greek language from poly “many” and meros “parts”. Polymers are large molecules consisting of repeating identical structural units connected by covalent chemical bonds. Polymers can be naturally occurring or manmade. Manmade polymers are materials like nylon, polyester, and polystyrene. Examples of naturally occurring polymers are proteins in our body like tubulin and actin. These proteins make up microtubules and microfilaments that serve as structural components within our cells.

Storage and Safety Guidelines:
Store Slime in an airtight container for about 3 weeks of use. Slime is non-edible. When you are through with it, discard in a trash container. Do not wash down the drain.

Who would have thought that soap could be so much fun? Not only does Ivory soap float in water, but if you heat it in a microwave it will expand into a mass of soap about three times larger than the bar. This experiment also generates some strong soapy smells – so be prepared!

What you need:

• Bar of Ivory™ Soap and another brand of soap
• Paper towel
• Microwave oven
• Bowl of water

HAVE AN ADULT HELP WITH THIS EXPERIMENT!

What to do:

1. Drop the bars of soap into the bowl of water. Notice how one floats and one doesn’t.
2. Remove the Ivory soap from the water. Break it in half and notice if there are any air pockets.
3. Place the Ivory soap in the middle of a paper towel and place in a microwave on HIGH for 2 minutes.
4. Observe what happens to the soap! Don’t over cook your soap soufflé! Allow your soap to cool for a minute before touching it.

What’s the science?
Ivory soap floats because it has air pumped into it while it is being made. It also contains water, both in the form of water vapor trapped in air bubbles and water in the soap matrix itself. The heating of the water that is inside the soap causes the expanding effect. As the water vaporizes, air bubbles are formed. The heat causes trapped air to expand and the soap to soften and become pliable.

This is an example of Charles’ Law which states that as the temperature of a gas increases so does its volume. When the soap is heated, the molecules of air move faster and move farther apart from each other. This causes the soap to puff up and expand.

• Apples (bigger is better)
• Knife (a butter knife will wok just fine)
• Potato peeler
• A few tablespoons of lemon juice
• 1/2 cup of salt
• 4 cups of water
• String

Start with a nice big apple that has the stem still attached. You will eventually hang the head to dry from the stem so keep it attached. If your apple is missing a stem you can thread a wire through the core and use a large button to support the bottom of the head. Remove the skin from the apple with the potato peeler or knife. You can leave a little at the top and bottom. A freshly peeled apple will begin to brown as the oxygen in the air begins to oxidize the surface of the fruit. We can slow this down by coating or dunking the fruit in a mixture of lemon juice and salt.

One of the hardest parts of carving a shrunken head to where to start? I’ll show you how I carve my heads, then you can use this as a starting point for your own creations. Step one is to create the ears. Turn your apple so you have plenty of working material on the sides. Start by marking off a big square on the side. Now remove the fruit around the outside of the square to reveal a sort of blocky looking ear.

Shape up the ear by cutting the corners back and boring an ear canal. Remember, we are going to shrink this head so carve the features BIG. Small details will be lost after shrinking so go for really BIG features. Once you have one ear completed, turn you head around and make another one on the other side. If you want the ear to really look good when dry, carve a little indent around the base where it attaches to the head. When dry the ear will have a bit more depth.

Now to start the face outline the forehead and nose with a few simple lines. Once you have this in place bring your knife in from the sides to create an eye socket. You may want to cut the lines around the nose a bit deeper than the forehead line. Be careful when making the eye sockets that you don’t pop off the nose! Use a pencil or chopstick to create a hole for the eye in the socket. Once the apple is dry you can push in a whole clove or pepper corn here for an eyeball.

Under the nose carve a little space to separate the nose from the lips. If you nose is really big, you might be able to drill in two nostril holes that will show up when dry. If you nose is small don’t bother. Often you won’t have enought material for a big set of lips since the bottom of the apple usually tapers down. If you have enough, make them big and make sure to make an upper and lower lip. Cut a deep slit between them so as they dry they will become separate lips. Another option for the mouth is to just make a deep cut and when things are all dried out you can add some dry rice for teeth!

Now you are ready for the salt water soaking. Ideally you want to soak your head for 24 hours in the salt water. This will help draw water out of the apple to help with shrinking. If you’re impatient, just give it a short soak and then hang it up to dry. Ideally you want a nice dry location for your head. I would avoid trying to dry the head in a moist bathroom! You can speed up the drying process a bit by placing the apple in the oven at a really low temp (~150 degrees) for an hour or two before setting aside to dry. After about 1-2 weeks your head should be ready. Be sure to check on your head periodically and if any mold is growing you can remove it with a cotton swab.

If you really want to dress up your head, you can add whole cloves for eyes, maybe rice for teeth, some yarn or fake hair on top might look nice. Add coloring to your head with charcoal or use food coloring as a paint. If you have an old Halloween wig around you can use some of that hair to make it look more spooky. It’s up to you! While I’ve never tried it, I’ve heard you can use a craft sealer, wood sealer or shellac to seal and preserve your head. Make a few heads and experiment to see what works for you.

That’s it! Use your imagination, have fun and let us know how it works for you!

Cookie mining is a fun activity that might get you thinking about what it take to mine for minerals in the Earth’s crust. Can you extract the minerals without making a mess or destroying the materials around it?

What you need:

• Chocolate chip cookies
• Toothpicks
• Paper plates

Before you start:
The earth’s crust is made up of soil, rocks and minerals. Rocks are made up of a combination of different minerals. Rocks are also mined to find minerals. Taking care of the earth is very important. When we mine for precious stones and minerals, we do not want to harm the earth around the rocks. In this activity, you will be a miner for precious gems. Your cookie is the earth and the chips are gemstones.

What to do:

1. Place a chocolate chip cookie on a paper plate.
2. Use a toothpick like a real pick to mine the chocolate chips out of the cookie.
3. See how many chips you can poke out of the cookie and still keep it in one piece. Be careful not to break the cookie. How many chips were you able to mine?
4. After you’ve finished mining your cookie, you can eat it.

What’s the Science?
Mining is the extraction of minerals or rocks from the earth. The minerals that are recovered from the earth through mining include silver, copper, salt, petroleum, gold, and lead. Some of the rocks include coal, diamonds, granite, marble, and emeralds. These materials can be used to make many different things. Some examples include coal, which is used as a fuel, copper which is used in electrical conductors, and lead which is used in making car batteries.

Here’s a way to make a simple make bubble making device using things around the kitchen.

What you need:

• a straw (the non-bendy kind)
• string
• a pie tin (or bucket or tray)
• scissors

What to do:

1. Cut your straw in half.
2. Thread the string through both straws and tie the ends together to make a loop. Trim off any long string ends.
3. Place your bubble building apparatus into the bubble solution.
4. As you take it out of the bubble solution, pull the two straw pieces away from each other so that you make a rectangle with the straws and string. Can you see colors in the film?
5. Try gently blowing a bubble. What shape is it?

What’s the science?
The colors observed on the outer surface of a bubble are caused because waves of light interfere with each other as they pass through or bounce off of the bubble. This interference causes certain colors to appear and disappear. As you closely observe your bubble window you will notice that the colors seem to flow toward the bottom as gravity pulls the bulk of the bubble film downward. The bubble film becomes so thin right before it pops that it appears black. Try watching for this black area in your bubbles or bubble windows… impress your friends with your *pop* predicting abilities!

Try making other types of bubble makers … you could use pipe cleaners, string, a colander or strainer, your fingers, a straw, a toy … your imagination! Try thinking of as many things as you can to build bubbles! What can you do to make big bubbles? Small ones?  Can you build a bubble as big as your head?

Are black inks all the same? This experiment will allow you determine what colors are combined to make black ink in some common water based markers.

What you need:

• Coffee filters or paper towels
• Water
• Various colors of water soluble markers
• Various brands of black water soluble markers
• Pipettes or medicine droppers
• Plastic cups

What to do:

1. On a coffee filter or paper towel, draw a circle with the black marker of your choice.
2. Place your paper on top of an empty plastic cup.
3. Using the pipette, drop water, by droplets, onto your paper in the center of the circle you drew with black marker.
4. Slowly add drops of water until the water starts to “bleed” through the black circle. What appears to be happening?
5. Repeat this with the other brands of black markers. Are there any differences?
6. Repeat steps 1-4 again using the colored markers. With which colors do you see multiple color bands appearing in the water run? With which colors do you see no other color bands? Can you use this method to blend colors?

What’s the science?
The word Chromatography comes from the Greek words for color (Chromato) and writing (graphy). It is a method of separating mixtures using a solid support plus a liquid solvent. In every kind of chromatography, a mixture separates because some of its components stick better to the solid so they stay behind. These components have a strong affinity or attraction for the solid. Other parts of the mixture dissolve in the solution that wicks into or across the solid.

The end result is that you see bands of color that separate out on the solid support. When using colored markers, this “color-writing” or chromatography process allows you to determine what  inks are mixed together to make a  particular color of marker.

Recipe for Oobleck

To mix up some Oobleck grab a box of cornstarch, some water and a mixing bowl. In general, a mixture of about 1.5 cups of cornstarch to 1 cup of water is a good starting point. You will have to tweak these amounts to get the perfect mixture. Keep in mind that the mixing process can get messy so be prepared to clean up.

• Cornstarch
• Pitcher of water
• Aluminum pie pans
• Measuring cups
• Mixing spoon
• Newspaper for covering tables
• Food coloring or tempera paint (for fun)

Pour the cornstarch into a large mixing bowl and slowly add the water. You are shooting for a mixture that feels kind of like honey and tears a bit when you run your hands across the top. You will have to experiment with more or less cornstarch or water until you get the right mixture. If you want to color your Oobleck add some tempera paint. You can use food coloring if that’s all you have on hand. Food coloring tends to stain more than the paint, especially if you have a spill while preparing your Oobleck.

One thing to keep in mind is that Oobleck is a suspension, not a solution. The cornstarch does not dissolve in the water like salt or sugar would. Instead, the tiny starch particles are suspended in the liquid. If you let it sit long enough in a glass, the cornstarch will settle to the bottom leaving a layer of clear water on the top. This is why it is very important to not pour Oobleck down the drain. Should the suspension separate in your drain pipes, you will be left with a hard clump of cornstarch that will block the drain. The best way to get rid of you Oobleck is to simply put it in your trash can.

What does non-Newtonian mean?

All fluids have a property known as viscosity that describes how the fluid flows – commonly thought of as how thick or thin a fluid is. For instance, honey is much more viscous than water. When a fluid’s viscosity is constant it is referred to as a Newtonian fluid. Oobleck is an example of a fluid whose viscosity is not constant, it changes depending on the stress or forces applied to it. If you poke it with your finger and apply a large force, it becomes very viscous and stays in place. If you gently pour it, applying little force, it will flow like water. This kind of fluid is called a dilatant material or a shear thickening fluid. It becomes more viscous when agitated or compressed.

Another non-Newtonian liquid is ketchup. Ketchup behaves in just the opposite way from oobleck. It becomes less viscous when agitated. Liquids like this are called thixotropic. If you leave a bottle of Ketchup on a shelf, it becomes thicker or more viscous. Nearly everyone has experienced this while trying to pour the liquid from a new bottle – it refuses to move. If you shake the bottle or stir it up it becomes less viscous and pours easily.

Why does Oobleck behave the way it does?

The most generally accepted explanation for the behavior of Oobleck is offered by Cary Sneider in “Oobleck: What do Scientists Say?”. When sitting still the granules of starch are surrounded by water. The surface tension of the water keeps it from completely flowing out of the spaces between the granules. The cushion of water provides quite a bit of lubrication and allows the granules to move freely. But, if the movement is abrupt, the water is squeezed out from between the granules and the friction between them increases rather dramatically.

Experiments to try

The first thing you have to do is simply place your hands into the Oobleck and start squeezing it. Have some fun! Try to make a ball by moving it around quickly in your palms. Once you stop applying pressure to the mixture it will flow out of your hands like a liquid.

Try filling a pie plate with a think layer of Oobleck and then slapping the surface with your open hand. Because of the dilatant properties, becoming more viscous when a force is applied, the liquid will all stay in the plate. Try the same experiment with water and compare the results!

If you have a lot of cornstarch and a small pool (or a large one like in the video) you can supersize this experiment. Since the liquid becomes more viscous when pressure is applied you can actually walk or run on the surface without sinking. Of course, once you stop moving you will begin slowly sinking into the liquid.

Another fun experiment is to fill the cone of a speaker with some Oobleck. Connect the speaker to a low frequency sound source and watch as the Oobleck seems to come alive. Typically low frequencies get the fluid up and moving better than higher pitched sounds. A plastic subwoofer works the best, or you can use a sheet of plastic wrap to protect a paper cone speaker.

Film canister rockets are always pretty amazing considering all that powers them is a little bit of Alka-seltzer and water. The launching time is always a bit unpredictable and that just adds to the fun.

What you need:

• Paper, Index cards or cardstock,
• Translucent film canister, Tape,
• Scissors, Effervescing antacid tablet,
• Water and Paper towels

What to do:

1. Wrap and tape a tube of paper around the film canister. The lid of the canister goes down.
2. Cut fins from the index cards and tape to the rocket.
3. Make a nose cone by cutting a circle out of paper. Cut out a pie shape from the circle and twist the paper into a cone. Tape the cone together. Then tape it on the open end of the paper tube.
4. Turn the rocket upside down and fill the canister 1/3 full with water.
5. Work quickly! Drop in a 1/2 tablet and snap the lid on tight.
6. Stand the rocket upright and stand back!

CAUTION: Be careful when launching your rocket. Stand back and don’t point it at anyone.

What’s the science?
As the antacid tablet “fizzes” carbon dioxide inside the canister, pressure from the gas builds and eventually pops the lid off. The amount of force, or push, created is related to the amount and speed of gas and water propelled from the canister.

What will happen if…

• you change the design of your rocket?
• you use more or less “fuel?”
• you use hot or cold water?

Choose one thing to change (that’s the variable), then predict what you think will  happen and test it.