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What You Need:

• Your Favorite Drink (Soda, orange juice, lemonade, etc.)
• Quart-size zip-lock bag
• Gallon-size zip-lock bag
• 2 cups ice
• 1/4 cup salt
• Bowl

Fill the quart size bag with your favorite drink and zip it closed. HINT: Make sure the bag is zipped really good or your slushie will taste bad when some of the salt leaks into your bag. Put the quart size bag inside the gallon bag. Add the ice and salt to the gallon bag. Zip the gallon size bag closed. Now shake the bag a lot – even play catch with it…gently. In about 15 minutes you will feel the ingredients in the quart size bag starting to firm up. What started out as a liquid is changing to a solid. When it feels done take the quart size bag out of the gallon size bag. Rinse it off good in clean water. Then open the bag, squeeze the slushie into a glass and enjoy!

TIP: It’s OK for a dog to lick the ice, it won’t be in your drink anyway. Tip for the dog…lick the ice BEFORE the salt goes in!

And if you’re feeling like something with a few more ingredients, try this, ziploc bag ice cream!:

Your favorite drink is a liquid until it gets really cold.  Your liquid drink would be pretty good with ice just floating in it…the ice cubes would make the drink colder…but the ice cubes would not make the drink freeze into a slushie.

Ice forms when the temperature of water is 32 degrees or colder. You don’t want the ice cubes to melt IN your drink, you want your DRINK to turn slushie. In order to make your drink turn slushie you have to get it really cold. Salt lowers the melting point of water. To make a slushie you want the temperature around the bag of your favorite drink to be lower than 32 degrees so your drink will freeze. When you add salt to the ice cubes you lower the melting point of the ice cubes by several degrees. The ice cubes stay colder, longer – long enough to turn your drink slushie. Your salt/ice mixture will make your slushie faster than your freezer! That secret is the catalyst – the salt.

Science Experiment Idea: Make 3 different quart size bags each filled with the exact same amount of your favorite drink. Fill each of three gallon size bag with the exact same number of ice cubes. Add 1/8 cup of salt to the first gallon size bag and label it with a sharpie, “1/8″. Add 1/4 cup of salt to the second gallon size bag and label it “1/4″. Add 1/3 cup of salt to the third gallon size bag and label it “1/3″. Have a couple friends help you shake and smoosh the bags to make the slushies. Time how long it takes each of the bags to turn into a slushie. Which amount of salt makes a slushie the fastest?

Here are some websites and books that will help you understand the thermodynamics of slushies…and ice cream too!

• PBS Kids: Fetch Ice Cream Shake
• The Children’s Museum of Indianapolis: Virtual Hotshop

Words to Know:
Heat - To increase in temperature.
Melting Point – The temperature at which a substance will change from a solid to a liquid.
Thermodynamics – The study of the transfer of heat.
Catalyst – Something that makes a change happen faster.

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Gravity is the force that pulls objects toward the center of the Earth. An object’s center of gravity is the average location of the weight of the object.

If you have a wooden ruler you can balance it on your finger at the 6 inch mark. The ruler has a uniform shape and it’s weight is evenly distributed along its shape. It is easy to determine that the 6 inch mark, right in the middle, is the center of gravity for the ruler. There is an equal amount of weight on each side of the 6 inch mark; the gravitational pull on both sides of the rule is equal - so the ruler will balance.

If you have an object like a person trying to balance on a balance beam, then it is a little trickier to figure out where the center of gravity is located. It will be a little different for each gymnast depending on how their weight is distributed on their body. Each gymnast learns the location of their own center of gravity and knows to keep that point centered over the balance beam. If that point is not centered, the gymnast will fall off.

In today’s experiments you will find the center of gravity for objects that are not as easy as a ruler, you will find the center of gravity for a pop can and a fork.

What You Need:

• an Empty Soda Can

Here is a video that will show you exactly what to do to balance a pop can:

I tried the pop can and it really did work. It only took a couple tries too. It is a little harder to tap it and make it go in a circle.

Balancing the two forks is a little harder.

What You Need:

• Two Identical Forks
• Toothpicks
• Salt Shaker
• Empty Pop Can
• Water

First, stick a toothpick in the center hole of a salt shaker. This will act as your balance point. Now take the two forks and press the tines of the two forks together, making them into an “L” shape. Hold a toothpick in your hand and try to balance the forks on the toothpick. Once you get the forks balanced, transfer them from the toothpick you are holding to the toothpick stuck in the salt shaker. The girl in the video makes it look easy. Not easy!

Here are some websites and books that will help you understand and play with gravity:

• Physics4Kids: Gravity
• StarChild: What is Gravity
• Fetch: Set it Straight
• ZOOM: Weightlessness
• Tryscience: Gravity in Action
• PBSKids Fetch: Skydiver
• PBSKids Fetch: Stack ‘Em Up
• PBSKids Fetch: Throw Your Weight Around
• The Guardian: Perfect Balance Nails
• Bill Nye Falling for Science
• Bill Nye Weightless Clothespin
• You can find the directions for this experiment at Steve Spangler Science: Balancing Forks and in Steve’s book Balancing Forks (page 51).
• Gizmos and Gadgets Chapter “All Fall Down” about Gravity (Pages 49-67).

Words to Know:

Gravity – The force that pulls everything toward the center of Earth; the force of gravitation on Earth.
Center of Gravity - The average location of the weight of an object.
Weight – A measure of the force of gravity upon an object
Balance - An even distribution of weight so that an object will remain upright and steady even if it is resting on a very small point.

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A couple weeks ago we learned about centripetal force when we did the Hex Nut Balloon experiment. We learned that centripetal force is what makes an object move in a spiral pattern when it is travelling in a circle, like a penny in a funnel shaped wishing well. Centripetal force is the force that pulls a thing toward the center of rotation….like the little whirlpool that forms when you drain the bathtub or like the Zinga at Holiday World! Why IS that water slide called Zinga? Because in Swahili Zinga means “to move in a circular motion”.

Today, we are going to learn about how liquid and air behave when they are moving in spiral pattern. Have you ever put a coin in one of those wishing wells that is shaped like a giant funnel? The coin rolls around and around the sides of the funnel in smaller and smaller circles until it goes down the hole in the middle of the well? That coin is demonstrating centripetal force. What You Need:

• 2 Liter Soda Bottles
• Duct Tape
• Water
• Food Coloring (Optional)

The tornado in the bottle looks a lot like the water draining out of the bathtub. When liquids pour they make a spiral pattern around a center. This is called a vortex. Gravity is pulling the liquid down toward the hole while the force of the pouring water is rotating around a center point…the middle of the drain or the neck of the liter bottle.

• Bill Nye Home Demo: Twistin Tornado
• Steve Spangler Science: Tornado in a Bottle
• Weather WhizKids: Tornadoes

Words to Know:

Centripetal Force – A force that makes an object move in a  circular path toward the center around which the object is moving. It is the force that pulls a thing toward the center of rotation.

Vortex – Whirling liquid or gas, like a tornado or the water draining out of a bathtub.

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What You Need:

• White T-Shirt
• Permanent Markers (Sharpies)
• Plastic Cup
• Rubber Band
• Rubbing Alcohol
• Dropper

Stretch part of the white t-shirt over the top of the plastic cup and secure it with the rubber band – it will look like a little drum. Choose one of the colors of Sharpie pen and make dots in the center of the t-shirt circle. Choose another color and make more dots. Repeat. The circle of color should be about the size of a quarter. Now slowly squeeze about 20 drops of rubbing alcohol into the center of the circle of dots. Drip the rubbing alcohol really slowly. What do you see happening to the ink? Let the ink dry for about 5 minutes and then you can move the cup to a different part of the shirt. When you are done making colorful circles put the shirt in the dryer for about 15 mintues to set the colors.

Sharpie pens are permanent markers. That means that the ink will not come off with water. If something will dissolve in water it is soluable. If something will NOT dissolve in water it is called hydrophobic. Permanent marker ink is hydrophobic. The permanent ink WILL dissolve in rubbing alcohol. That is why the colors “run” to make the pretty pattern.

Science Project Idea:

Try this method of tie dying with different kinds of markers and pens. Test whether the ink in the pens is soluable or hydrophobic. HINT: the word “washable” would be a clue to help you guess the answer to that question.

Here are some books and websites that will help you explore more about soluability and why sharpies and alcohol make such great 5 minute tie dye:

• Steve Spangler: Sharpie Pen Science
• Mess Free Tie Dye Shirts
• Instructables: Tie Dye Made With Sharpies
• Socks: Marker Tie Dye

Words to Know:

Soluable - Able to dissolve in water.
Dissolve – When a solid comes apart and spreads out into a liquid…like kool aid in water.
Hydrophobic – Not able to dissolve in water.

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The surface layer of liquids has a thin elastic “skin” called surface tension. You can see surface tension at work when you see a drop of water – it creates a little “bead” of water, like a little dome. Surface tension is what makes the dome shape – the water doesn’t flatten out.

Water is made up of two kinds of atoms, hydrogen and oxygen. The name for the water molecule is H20. The water molecule has 2 hydrogen atoms and 1 oxygen atom. Water molecules are attracted to each other because hydrogen atoms and oxygen atoms are attracted to each other and hug close together really tight. This is called cohesion. The molecules hug so close together they don’t want to touch other molecules around them. That’s why a bubble is round and only rests a small part of itself on a surface when it lands.

When you blow air into soap bubble solution the liquid molecules want to attract to each other again so they wrap around the burst of air until they can attach to each other again – this is what makes the round bubble shape. The air inside the solution is pushing the molecules in the soap bubble solution apart but the attraction between the soap bubble solution molecules is so great, the bubble doesn’t pop – the molecules are hugging each other too tight.

To experiment with bubbles you need a good bubble recipe. Below are some simple recipes to try. Each of the recipes use water and dish soap. The “other” ingredient can be baking powder, corn syrup, glycerin (sold at the pharmacy) or sugar. We had the best luck with baking powder. The baking powder recipe made some HUGE bubbles.

Science Project Idea:

Mix different formulas of bubble mix and test them to see which one makes the best bubbles. Use the same amount of water and the same amount of dish soap in at least three different buckets. Choose one “Other” ingredient and add it in different amounts to each of your trial buckets. To be fair, you should hold the bubble wand in front of a fan instead of trying to blow on it, that way you know that the amount of air being blown to make the bubble will be exactly the same. Test the three formulas several times and record your results on a chart. Decide before you begin what property you are looking for in the bubbles. Are you going to test which formula makes the biggest bubble, the bubble the last the longest without popping or the formula that makes the most bubbles?

Here are some books and websites that will help you understand and have fun with bubbles:

• Exploratoriuam: Bubbles
• Bubblesphere
• Homemade Bubble Solutions
• The Ultimate Bubble Book There are 3 fun activities in this book – Person Inside a Bubble (Page 41) Giant Bubbles (Page 48-51) Printing With Bubbles (Page 52-53)
• Google Preview: Science Experiments That Explode and Implode: Stink Bombs (bubbles that stink! pages 22-23)
• Prize Winning Science Projects for Curious Kids: The Bubble Olympids (pages 102-103)

Words to Know:

Surface Tension – The film that forms on the surface of liquids caused by the attraction of the particles in the surface.
Cohesion – The attraction between like molecules; to stick together.

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