A Density Experiment You Can Drink!

Density is a fascinating and sometimes tricky idea to understand. This Drink of Density will help bring home the idea of density in liquids, not to mention it looks cool when your all done, it’s tasty, and it’s even good for you – what more could you ask for in a science activity!

You will need:

• Juices that have different density levels. (see below for a simple explanation of density) The density of a juice is often determined by how much sugar or fruit is in it – the more sugar or fruit, the more dense the juice is. Powdered and canned juices do not work well for this experiment since they are almost entirely water. You will have to do some experimentation to find juices that are colorful and give a nice display of density, and that’s half the fun.
• A narrow glass (the more narrow it is, the easier it is to separate the density levels)
• Eye dropper or turkey type baster.

What to do:

1. Before you begin, you can guess which juices you think will be more dense and form a hypothesis of how the levels of your Drink of Density will turn out. Check the number of ingredients, the sugar content, and the water content to help you out.
2. In order to display your density levels, you will need to find out which of your juices are the most and least dense. Pour one of your juices into the narrow glass to fill it about 1 inch (2.5 cm) high. Fill a dropper with another juice and slowly drop it onto the inside of the glass so that it runs down the side of the glass. Watch the juice to see if it goes below or above the juice in there. (if it simply mixes with the juice and does not go above or below, it has the same density as the juice and you will need to move on to your next juice.
3. Continue experimenting with other juices to determine which juices go to the bottom (more dense) and which ones go to the top (least dense.)
4. Once you have the densities determined, start over with a clean glass and use the dropper for each level to create your final Drink of Density!

Note: In case you were wondering, the juices in the photo are (top) Tropicana Pomegranate-Blueberry, (middle) Tropicana Pure Premium Orange Juice, (bottom) Nature’s Promise White Grape (33 grams of sugar in 6.75 ounces!)

How Does It Work?:

The density of liquids demonstrates the the amount of “stuff” (atoms, mass) that are present in a particular volume of the juice. In other words, if you have cup with 200ml of plain water, and a cup with 200 ml of water that has lots of sugar dissolved in it, the cup of sugar water will be heavier even though they are the same volume of liquid – the invisible sugar molecules are dispersed in the water, making it heavier (more dense.)

Eggshell Geode Crystals

 Print This Post

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.

Do Birds Care What Color Their Food Is?

Would you want to drink green milk, how about orange mashed potatoes? The color of foods might affect just how much you want to eat them, but what about the birds in your neighborhood, would they care what color their food is? This sounds like an experiment in the making…. you coul even try this out for a science fair project, or just to learn something new while making your locals birds happy.

You will need:

• Several bird feeders that are the same size and type
• Light colored birdseed appropriate for the birds in your neighborhood
• Several colors of food coloring

QUESTION -  What color of birdseed, if any, will birds prefer the most?

RESEARCH: Ornithologists (scientists that study birds) are rather certain that most birds can see in color. One reason they think this is because birds themselves are very colorful.  In many species, male birds tend to be more colorful than females. This is likely because the males use their coloring to attract a mate,  while female birds tend to have less coloring to provide camouflage as they protect their eggs in the nest.  Before beginning a large experiment with lots of bird seed, you may want to put out a few small handfuls of different colored birdseed (see instructions for coloring birdseed below) to see how the birds near you react to different colored seed.  You may also want to refer to books and talk to an ornithologist to get their opinion about how birds see the word.

MAKE A HYPOTHESIS: Use the information that you’ve gained from your research and make a hypothesis based on your question. An example might be “Birds will eat more green birdseed than other colors.”

EXPERIMENT:  This is the fun part. You should get several bird feeders that are all the same size and type. Purchase a bird seed that is very light in color for this experiment.  To color the bird seed, pour it into a bowl and then add food coloring that you can purchase from the store. Mix it up well with a spoon and continue to add color until all the seed is colored.  You should sample at least a few colors and have one feeder with seed that has not been colored -  this is called the control and it will give you something to compare your results to. Now just hang them up outside in the same location, and wait for your feathered friends to show up. This works best in an area that birds are used to feeding from a feeder – it can take birds over a week to find new feeders.

COLLECT DATA:  Observe your bird feeder whenever possible, and keep track of how much seed is in each bird feeder each day. A ruler is helpful for this. You might also want to take pictures of the feeders and keep track of which kind of birds visit each feeder.  Over time, you should be able to see if one color of seed gets eaten more than others.

MAKE A CONCLUSION: Once your experiment is done, you will be able to go back to your hypothesis and see if it is correct. Remember,it’s not bad if your hypothesis was wrong. The main thing is that you’ve learned something from your experiment, and hopefully you had some fun doing it.

If you try this, let me know how it goes!

If you need inexpensive bird feeders, you can get some on-line HERE.

Oobleck – The Corn Starch And Water Experiment

 Print This Post

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…and clothes…and curtains)
• 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 your 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

The Lincoln High Dive – A Newton’s Law Experiment

Goat a few minutes? Here is a simple experiment that has impressed both students and adults that have tried it. It is also a great way to observe Newton’s First Law in action.

You will need:

• A Lincoln penny (or other small coin)
• A piece of card stock or stiff paper
• A film canister (baby food jar, juice bottle, other  container with a mouth that is a bit wider than a penny)
• Pencil or pen
• Scissors

1. Cut the cardstock paper into a long strip about .75 inches (2 cm) wide and form it into a hoop as shown. The paper should be stiff enough to hold the hoop shape on its own and the hoop works best when it is between 3-4 inches (8-10 cm) across.
2. For dramatic effect, fill the film canister with water and place on a level surface.
3. Place the hoop on the film canister as shown and balance the penny on the top of the hoop.
4. Time for Lincoln’s big moment! Place a pencil through the center of the hoop and in one swift motion fling the hoop off to the side. If you do this correctly, the hoop will fly out of the way, and the penny will fall straight down into the canister with a splash. 10 points for Lincoln!

This is science?
You betcha. For this demo, Newton’s first laws says, in general, that an object at rest will remain at rest unless acted upon by an outside force. The energy of your movement with the pencil was passed on to the hoop, making it fly out of the way, but the hoop was moving too fast and there was not enough friction to affect the penny (at rest) on top of the hoop. The penny ended up above the film canister with nothing to hold it up. It was about then that gravity took over, and pulled the coin straight down into the waiting water. Yep, Issac Newton and Abraham Lincoln, together in the name of science.

Try it out and post here to let us know how it goes! Experiment with various hoops and objects to make it different.

Classroom fun with The Fizz Inflator

What would the science world be without vinegar & baking soda? It would be a little less exciting at the Community School of West Seattle. Michelle Taylor teaches a K-2 program there and she decided to add a little science excitement to her classroom. With a little vinegar, baking soda, a bottle and a balloon, her students were able to to observe chemistry at work inflating the balloon. (Instructions for this experiment below)

“You could hear the screams all through the school – it was so exciting.”

For instructions to this experiment, CLICK HERE.

To visit Michelle’s classroom blog, CLICK HERE.

.