Note:  Some balloons are likely to pop loudly during these activities. Keep balloon bits away from small children and pets.

Gather:

• large balloons (12″ party size)
• bamboo skewers
• metal hexnuts (as smooth as possible – see photograph)
• dish detergent and/or vegetable oil
• paper plate

Activity 1. Can you insert a bamboo skewer through an inflated balloon without popping it?

The answer is yes, but it requires a bit of knowledge. First, it helps to lubricate the skewer with a bit of dish detergent or vegetable oil. Place the soap or oil in a paper plate and roll the skewer in it.

Inflate the balloon and tie it. The idea is to insert the skewer in the areas of least tension, which is where the latex is darkest, typically where the balloon is tied and directly opposite at the tip of the balloon. Gently work the balloon into the area near the knot and pass it through the center of the balloon. Using a brisk motion, slide it back out through the balloon at the top.

Now you have an inflated balloon on a skewer!

If you used soap, experiment and try oil. What happens if you try to put the skewer in where the latex is thin (nearly clear)?

Activity 2. Making a balloon sing.

Have you ever let air out of an inflated balloon and had it screech?

You can also make a balloon “sing” by inserting a metal hexnut into the un-inflated balloon. Once the hexnut is inside, inflate the balloon as usual and tie it. Now rhythmically shake the balloon. The idea is the get the hextnut to whirl around, creating a vibration. Once you get the hang of it, experiment. Does how fast you whirl it change the pitch? How about the size of the balloon? What happens when you add two or more hexnuts? Make a prediction and then test it.

hexnuts

Activity 3. Decorate a balloon with cups.

For this one you’ll need:

• rigid plastic cups- 6 oz size
• water supply
• balloons

Lightly wet from four to six plastic cups. Begin to inflate the balloon until it is about the size of two fists. Press one cup on the balloon surface and continue to inflate slowly. The cup should be held in place by air pressure. Press another cup. See how many cups your balloon will hold before it is fully inflated. If you are having difficulty, try pressing the sides off the cup in a little bit prior to applying. This one takes a little practice, but it does work.

Activity 4. Fast flying balloon.

Have you ever let go of a balloon that is blown up fully, but before you tie it. Did it fly around the room? You can harness that thrust to study it.

This is easier with at least two people.

Gather

• long, narrow balloons (work best for this)
• kite string at least 15 feet long
• tape
• straw (preferably wide and not the bendy kind)

Tie one end of the kite string to a doorknob, chair or stair rail, below the height you can reach. Feed the other end of the string through the straw and back up to hold the string tightly. Test if the straw will travel freely down the string to the other end. Bring the straw back and either have someone hold the end or tie it to another surface that is at the same height or higher than the first. Inflate the balloon, but don’t tie it. Tape the straw to the inflated balloon so that the open end of the balloon faces back. Release and let the balloon shoot along the string.

See if you can modify your set up to make the balloon travel faster.

Additional resources:

A classic activity is to inflate a balloon using vinegar and baking soda.

Steve Spangler has some ideas using balloons as well. Can you keep a balloon from catching fire?

He also has a balloon in a bottle.

The Book of Totally Irresponsible Science: 64 Daring Experiments for Young Scientists by Sean Connolly contains versions of these experiments.

With a tin can, you may investigate sound vibrations, friction, kinetic energy, potential energy and many more aspects of physics.

Before we start the physics, however, let’s do a bit of chemistry.  Is what we call a “tin can” really made of tin? How would you check?

It seems that the can our beans come in should be called a steel can because it is made mostly of steel, although it may have a light coating of tin to prevent rusting. Technically, if a can were made only of tin a magnet should not stick to it. Magnets are attracted to cans that contain iron, usually in the form of steel. Is a magnet attracted to your can of beans? What about an aluminum soda can? Pick up a magnet and find out.

What got us started with tin cans this week was an article in a book that promised you could get a tin can to roll uphill. When it did not work as the book suggested it should, we decided to investigate further.

Activity 1. Uphill Rolling Can

Gather:

• Clean, empty tin can* or similarly-shaped plastic container
• modeling clay
• cookie sheet or similar flat surface and a couple of books to make an adjustable ramp
• rubber bands (optional) to give the can more grip

* Remove the lid of the can with adult supervision, and make sure there are no sharp edges.

Roll the can across the floor or on a table to see how it behaves. Build a ramp with a slight incline with the books. Try to roll the empty can up the ramp. What happens?

Now roll out a lump of the clay into a worm or snake shape. Attach the clay to one side of the can on the inside (see photograph). Roll the can across the floor or table. Does it behave differently than it did without the clay?

Try the ramp. Start the can with the clay up versus the clay down, until you can get the can to roll uphill. If it doesn’t work for you, adjust the steepness of the ramp. You can also put rubber bands around the outside of the can to increase grip. Make sure they are even so they don’t over balance the can.

Check this description of the uphill roller at CSIRO.

Activity 2. Tin Can Car

You can take the idea of a self-propelled tin can a step further by creating a rubber band-driven version.

The idea is to put two holes in each end of the can (or can lids) that line up with each other, slip a rubber band (or similar elastic material) through the top holes and then add a weight in the center, in the middle of the can. Slip rubber bands through the bottom holes. Tie the ends. Roll the can and it should roll back on its own from the weight in the center.

PBS Kids has a good description of how to make a can car.

Description of a similar device from the November 1910 issue of Popular Mechanics. Be aware that ideas of safety were different back then. For example if you try this one, you should use a zinc sinker (available at fishing supply stores) rather than lead.

Activity 3. Tin Can Telephone

A classic activity is to make a telephone using two tin cans and a piece of string.

Gather:

• two clean, empty cans with the tops removed (or plastic cups work, too)
• nail
• hammer
• goggles (for eye protection while hammering nail into can)*
• string at least a few feet long

*Unlike in the video below, children should perhaps wear eye protection while creating the hole in the bottom of the can.

Hammer the nail into the center of the bottom of each can to create a hole. Remove the nail. Feed the string through the holes and tie a knot so that the knot prevents the string from coming out through the bottom. Both cans should now be connected by the string. Hold the two cans far enough apart so the string is tight. Take turns talking into the can and then listening to the other person talk.

You can even decorate your can like they did in this short video.

Activity 4. Musical instruments

1. Drum

Gather:

• clean, empty can or cans of various sizes with the tops removed
• large balloons, at least one per can
• scissors
• chopsticks (optional)

Cut the stem off of a balloon and roll it over the top of a can. This is not as easy as it sounds, but if you can get a tight fit you will have a wonderful drum. Use hands or chopsticks to drum on the balloon top. Compare sounds of different-sized cans.

2. Guitar

CSIRO has instructions on how to make a tin can guitar.

Activity 5. Sand Resistance (Advanced)

Gather:

• two cans
• play sand
• bin large enough to accommodate the two cans standing up plus sand

Fill a large bin with play sand. Press one can into the sand with the open end down. Press the other into the sand closed end down. Which has the most resistance? Sounds simple, but there are some complex physics involved.

To see the expected results, watch this video

For an explanation of the open can versus closed can in bucket of sand, see Science Now (website does contain ads).

A Few Other ideas:

Information about a stirling tin can engine in the Doable Renewables book review

Soda Can Robots

When you are done with your can, remember:

“…one plant in a tin-can may be a more helpful and inspiring garden to some than a whole acre of lawn and flowers to another.” ~ Liberty Hyde Bailey

Hope you have fun with your tin cans.

Let me know how the activities turn out and if you have any other ideas for science with tin cans.

This book just cries out for some hands-on activities.

Activity 1. Which type/brand of gum blows the best bubbles?

Gather:

• Several brands of bubble gum and regular gum
• Ruler (decide on inches or cm)
• Pair of tongs or cardboard bubble caliper (see below)
• Volunteer(s) to chew the gum and blow bubbles
• Paper and pencil to record the results

The most difficult part of this project is finding a standard way to measure bubbles that are often a moving target. Check this website for a photo of a “bubble caliper” used for measuring record bubbles. Think about how you might build something similar or find a pair of kitchen tongs that might open wide enough to accommodate the largest bubbles. Try to find the widest point of the bubble. Practice on a few bubbles to make sure your system works and is relatively consistent.

Predict which brand will produce the biggest bubble. Now give the volunteer(s) each one stick of each type/brand of gum. Allow them to chew the gum for a few minutes and then blow bubbles. When they are confident that they are blowing the best bubbles they can with that type of gum, have them blow a few more and measure them. Decide how many bubbles of each type of gum you are going to measure in advance, so you record the same number for each test.

When you are done, add up the size of the bubbles for each type, and then divide by the number of bubbles you measured for that type. This will give you an average. You might want to graph your results with a bar graph to easily see the differences between the brands/types.

Edit: Simply Science has a new review of the book and ideas for graphing your results.

Activity 2. What happens to the gum when you chew it? Does it gain weight from the moisture in your mouth, lose weight, or stay the same?

Gather:

• accurate kitchen scales
• gum
• wax paper to protect the scale (or the wrapper)
• watch or timer

First, predict what you think  will happen. Take the wrapper off the gum. Place a piece of wax paper on the scale, and tare or zero the scale. If your scale does not tare, the record how much the wax paper weighs. Next place the dry gum on the scale. Record the weight (subtract the weight of the waxed paper if you did not zero it). Leave the wax paper in place.

Now chew the gum for one minute and weigh again. Record the weight. Weigh again at five minute and then at ten minutes of chewing. What is happening? Did the results follow your prediction? Try to figure out why or why not. Test more sticks and different kinds of gum, and have your friends and relatives try it, too. See if you get the same results.

Activity 3. Make your own bubble gum.

This video shows how bubble gum is made in a factory.

You can find kits and online recipes to make your own bubble gum (for example at Steve Spangler).

Try some other formulas, too. Be sure to write down what ingredients and the methods you use. Maybe with some time and the right ingredients, you could be the next Walter Diemer and discover something thrilling and new.

Links to other activities:

How long does sweet flavor last? How much sugar is there in bubble gum? See an experiment at Teach Engineering.

Does chewing gum help you concentrate? Science News for Kids has some information about that.

Why is it sticky? Learn more about the sticky properties of gum at Science in School.

Do you chew bubble gum? Let me know if you try some experiments with it. I’d love to hear what you find out.

Pop! The Invention of Bubble Gum

A few other books and kits relating to bubble gum science:

Mike Rigsby is a professional electrical engineer and he has a noble cause for writing this book. He has come up with projects to investigate various forms of renewable energy in the hope at least one of them will spark a young person to discover something that will change the world. His projects include making engines that use heat as a source of energy (including one with nitinol springs), solar energy, wind energy and wave energy. Each project is explained clearly, with a detailed list of supplies and numerous black and white photographs showing the assembly, as well as the finished project.

Before we get too excited, though, let’s do the reality check. Safety is one concern. Some of these projects have steps that could potentially cause injuries, especially those that involve cutting. Unlike many of the activities found in children’s science books, some of these projects are not made from items lying around the house. Many will require the purchase of specialized pieces of equipment or supplies from science and technology suppliers. For example, the nitinol springs are available from Jameco Electronics, part number 357835. As of today, they cost $45.95 for a 4 pack. The bottom line is that this book is for serious older children or young adults who enjoy engineering and inventing, and who preferably have an experienced adult mentor.

That said, do you have a science fair coming up soon? Doable Renewables: 16 Alternative Energy Projects for Young Scientists is a wonderful resource sure to generate innovative science fair projects.

In fact, the book inspired us to do some of our own investigations:

1. Stirling tin can engine

In chapter 4, Mike Rigsby suggests purchasing a Stirling engine to explore this technology investigated by Reverend Dr. Robert Stirling way back in 1816 (see our Amazon suggestions below). The Stirling engine uses heat to do work, and is known to be very quiet in comparison to the internal combustion engine.

Rigsby also mentions that there are instructions for building your own on the Internet, so of course we had to look. We found quite a few examples of Stirling engines you can make at home plus numerous videos of the engines in action. Here is one example of a fan Stirling engine (note: there is a pop-up ad).

The instructions can be found at Easy to build Stirling engine

There is more about how Stirling engines work at How Stuff Works.

2. Radiometer

We already had a radiometer, so we dusted it off and tried it out. A radiometer is a glass bulb that looks like a light bulb. Inside are 4 tabs suspended from wires. Those tabs are reflective on one side and black on the other. When placed in sunlight, the tabs rotate like crazy.

The Crookes radiometer caused quite a stir in its time, because no one was quite sure how it worked. Several hypotheses were proposed and shot down. Eventually the idea of thermal transpiration was found to be the one most generally accepted. It involves the movement of gases from the warmer side of the tab (the black side) to the cooler, reflective side. In any case, the only energy supplied is that from the sun.

3. We have a previous post on Windmills and wind power that also relates to this topic.

We hope this inspires you to try a few new projects with renewable energy. Be sure to let us know how they turn out.

Reading level: Ages 9-12 (Amazon)
Paperback: 224 pages
Publisher: Chicago Review Press; Original edition (October 1, 2010)
ISBN-10: 1569763437
ISBN-13: 978-1569763438

This book was provided for review.

Stirling Engines at Amazon

Other scientific supplies suggested in the book:

Written and illustrated in a fun and energetic style, Rocks & Minerals is spot on for the target age group, 4 to 8-year-old children. The text lightly covers some common rocks, the rock types and how they form, the rock cycle and a few things humans have used rocks for. And it turns out the author, Steve Tomecek, is actually a geologist who studies soils. How cool is that?

As is always the case, we appreciate that the book contains two hands on activities. The first shows how mineral crystals can form when salty water dries up. The rocks that form this way are called evaporites. The second gives a recipe for making a rock at home (using pebbles and white glue). The author then asks, “What type of rock have you created?” In a stroke of pure genius, the answer on the next page is printed backwards, so you have to go find a mirror to read it. What a wonderful way to make sure the child actually thinks about the answer before having it appear.

To celebrate Rocks & Minerals, here are some of our activities:

1. For beginning geologists – Exploring a rock

A super way to learn more about rocks is to explore a few samples with all your senses. Pick up a rock that catches your eye. Close your eyes and hold it. What does it feel like? Is it cold? Is it rough? Is it heavy or light? Can you scratch it with your fingernail? Is it soft or hard?

You may feel silly at first, but smell the rock. What does it smell like?

Now, look at it very closely. What colors do you see? Is it sparkly or dull? Is it all the same over the entire surface, or does it change in places?

If you have one available, look at your rock under a hand lens or a microscope. What can you see now?

2. Making a rock collection – for many age groups.

Most young children seem to want to bring home rocks from their daily explorations. Use these as opportunities to learn about classification. Keep the rocks in a box or other container.

When you have accumulated a few, pull them out and ask your child to sort them into groups. He or she might make up his own categories at first, such as red versus brown or big versus little. Gradually, you can introduce the ideas of rocks types:  sedimentary, igneous and metamorphic (see video below if you are rusty on these terms).

Later your child may want to identify rocks and minerals he or she has collected in a more scientific way. At this point, it is important to begin to label each rock with such information as where and when it was collected. Take your child to see a geology museum or gem show to see how others display their rock collections. We are lucky to have a wonderful Arizona Mining and Mineral Museum in Phoenix, as well as some world famous shows, like the one in Tucson, plus a number of active organizations.

amethyst

3. Exploring the rock cycle – a noisy activity

Gather:

• plastic container with a tight-fitting lid
• a few small rocks, the rougher the better (polished rocks won’t work)
• piece of white paper or paper towel

Place the rocks in the container, and make sure the lid is shut tightly. Then let the children shake, shake, shake. After they tire out (or your ears tire out), open the container and pour the rocks out onto the paper. You should see the original rocks, plus bits of smaller particles that have broken off. Explain that when rock are tumbled around by action of water and wind, they break down over time. This is part of erosion.

obsidian

4. Now make a type of sedimentary rock called a conglomerate rock

Gather:

• sand, pebbles or bits of rock from the last activity
• Model Magic modeling compound or salt dough

Have the children press pebbles or sand into the modeling compound or salt dough and allow to dry. They have made a model conglomerate rock.

Mica

Pyrite

5. Float a rock

Obtain some pumice, a light volcanic rock with many air pockets, and a bowl of water. Ask the children whether rocks can float. Then place the pumice in the water to show that some rocks can indeed float.

Pumice

In this video from NASA see the rock cycle on earth and how it compares to the types of rocks found on the moon.

Do you have a rock collection? What is your favorite rock?

More about Rocks & Minerals by Steve Tomecek and illustrated by Kyle Poling:

Reading level: Ages 4-8
Hardcover: 32 pages
Publisher: National Geographic Children’s Books (November 9, 2010)
Language: English
ISBN-10: 1426305389
ISBN-13: 978-1426305382

Book was provided for review.

A perfect day to shoot off rockets.

You need a big area that is clear of hazards. You will also need a launch pad.

Whoosh and it is gone!

Check out that blue sky.

The parachute has deployed.

This rocket is almost down.

Whoosh! And here comes another one. In this case, it is rocket science!

To learn more about how rockets work, see NASA’s Beginner’s Guide to Rockets where they have a look inside a model rocket.

If you think you want to try model rockets, you should join a club or at least work with an individual who is experienced in the safe handling and launching of rockets. The National Association of Rocketry website has places to find a local club, a wealth of information about rockets, and a list of safety suggestions. And remember, often city, town and park regulations prohibit model rocket launches within their borders.

A question like this can often generate some interesting science.

Gather:

• a couple of sturdy mixing or soup bowls with sloped sides, at least two different sizes
• a straight-sided bowl, such as a casserole dish
• water
• metronome (optional)
• water-proof clothing such as a rain jacket (if it is cold out or if the children can’t change clothes if they get wet.)
• measuring cups (optional)

This is probably best done outside where a little spilled water won’t be a problem. First fill one bowl with water and see what happens when you walk with it held out in front of of you. Does the water begin to move back and forth? What happens when you stop?

Now compare that with a bigger or smaller bowl. Does more water go out over the edge with a big bowl or a small bowl? What about slope sides versus straight sides?

If you have a metronome, try walking at a constant slow pace versus a constant fast pace. See any differences?

You can actually make this more scientific by measuring the amount of water you put into the bowl and how much you have at the end with liquid measuring cups.

What we are seeing is the resonance, or the swing, of the water. When the swing gets big enough, over the edge it goes. This may not seem so important until you realize that the same sorts of forces are acting on the waves and tides of the oceans.

My son suggests I carry the water up the stairs in a straight-sided pitcher. Based on your studies, what do you think of that idea?

In Candy Bomber, pilot Gail Halvorsen releases small parachutes over the city of West Berlin after the end of World War II. The parachutes are carrying bundles of candy for the children whose lives have been disrupted by the aftermath of the war. Eventually the candy drops are turned into an official U.S. Air Force operation and more pilots join in. It is a heartwarming tale.

The challenge of building and testing parachutes would be a fun science activity to pair with this book.

A parachute consists of some sort of light material to form the canopy and suspension lines to attach the load.

Variables to test:

• parachute materials, such as cloth, plastic bags, paper, etc. Handkerchiefs were used in the Candy Bomber.
• canopy shape, such as square versus round
• canopy size
• length and/or number of suspension lines
• different shapes and types of candy

Some potential factors to measure:

• Time of descent (slower is better)
• Accuracy of parachute flight to a target
• Safety of load delivery (Does the candy land unharmed?)
• Distance traveled (if testing outside under windy conditions)

You will need a launch site. We drop ours over the balcony from the second story of our house to the first floor. You might try playground equipment at a park or school that has a stable, raised platform. Keep safety in mind.

Gather:

• materials to make canopies
• materials to make suspension lines, such as string or yarn
• measuring tape
• stopwatch
• assorted candy, individual pieces of hard candy with holes in the center would be the easiest.
• pencil and paper to record results
• scissors
• heavy-duty tape to attach suspension lines (optional, but may speed assembly) and to attach load

The simplest parachute to make is a square of material with strings tied to the four corners. Start with lines about 1 foot long. Tie the strings on the corners and bring the strings together at the bottom. Tie on a candy. A single hard candy with a hole in the center might be a good starting point, as long as your children are old enough.

Drop your parachute and measure one of the suggested factors. This is a great project to do with groups.

Here’s a somewhat long video that shows you more details of how to make toy parachutes.

Let us know what you find out about parachutes. Also, let us know what you think of the book.

1. Ice Spikes

Have you ever seen bumps or spikes come up from the ice cubes in your ice cube tray? SnowCrystals.com has a great discussion of ice spikes, how they form and how to grow some of your own. For more pictures and a movie, try Spikes on Ice Cubes.

2. Ice cube rescues

Give your child(ren) a challenge to “rescue” ice cubes floating in a glass of water with only a piece of string and some salt. Then watch this video to see how it is done.

3. Freezing and thawing water

Freeze water in various-sized containers and then set the ice “sculptures” out to thaw. (Set them in in deep bowl indoors or outside on a sidewalk or patio where a little melt water won’t matter.) Time how long it takes various sizes and shapes to melt with a watch or clock. Does size or shape influence melting time? How?

Try freezing a water-filled water balloon (set in a bowl first). Once it is frozen, what happens when you toss it? What happens when you freeze a balloon filled with air in a bowl of water?

4. Floating and sinking

Create an ice cube boat and float it to emphasize that ice is less dense than water.

Gather:

• ice cube tray
• cold water
• pie plate or shallow bowl
• plastic wrap
• toothpicks
• triangle of paper
• clay (optional)

Fill the ice cube tray with water. Cover the tray with a tight layer of plastic wrap, which will hold up the toothpicks. Stick a toothpick in the center of each cube, enough so that there is a least one for each child. When the ice cubes are frozen, remove from the tray. Insert a small triangle of colored paper on each toothpick to make a sail, and float the ice cubes in a bowl of cold water (the colder the better). Do the boats float? Do they stay upright? If not, try adding some clay to the bottom until the ice cubes are balanced. (This may be difficult at first, if the oily clay doesn’t stick to the wet ice. I found it did work with patience.)

5. Moving on to dry ice

Dry ice (frozen carbon dioxide) is available at many grocery stores. Just remember that it is much colder than regular ice and will require special handling. Always use gloves, and tongs are a good idea too. Never put dry ice in a swimming pool!

See this Steve Spangler video for some ideas and handling suggestions.

Ice is so much fun to experiment with in the summer. Let me know if you have any other experiments to do with ice or activity tips.

For more information, try these books:

and these related subjects:

Ice Scientist: Careers in the Frozen Antarctic (Wild Science Careers) by Sara L. Latta

Pioneering Frozen Worlds by Sandra Markle

Boats!

Children are fascinated by boats and floating. You can do a lot of interesting science projects with boats, starting with some basic questions: How can huge pieces of heavy metal float? How are boats propelled? Can you really make a boat out of paper?

We already have covered some floating and boat topics in previous posts.

Why Things Float contains some experiments on floating and sinking.

The How long can a paper boat float? challenge, with the early results for paper boats challenge.
The yellow legal pad boats lasted five days.

The Bathtub Buoyancy Challenge asked kids to find ways to propel boats across a bathtub without using their hands or electrical motors. The Bathtub Buoyancy results show several ways to propel toy boats.

It is always fun to build bathtub-sized boats. This video shows two handmade boats powered by battery packs and small electric motors that my son invented recently. A modified toy car powers the paddle boat; the air boat fan is a modified toy airplane propeller.

Why don’t you try inventing a boat?

For more ideas, try

A Simple Steam Boat at Curious Cat

Miniature Boats at HowStuffWorks

Hope you have fun and let us know what kind of boat you invent!

Edit: To check the rest of the posts on beach science, follow these links:

Sea Horses and Other Fish

Shore Birds

Tide Pool Invertebrates

Beach Science Algae

Beach Science-Sand

Beach Science-Seawater