Supercool

 - by KitchenPantryScientist

My posts have been spotty this summer, since I’ve been busy working on a follow up to Kitchen Science Lab for Kids.  Yesterday we supercooled water to see what would happen. It was tricky to get the temperature just right, but when we did, this is what happened!

To supercool water, chill purified water in your freezer, or in a cooler with salt water and ice. Chill an equal volume of tap water in the same cooler. Keep an eye on it. When the tap water is completely frozen, but the purified water isn’t, the purified water should be supercooled. Carefully remove it from the cooler, gently remove the lid and slowly pour it over an ice cube to duplicate the experiment above. If you drop it or jar it, it will probably freeze and you won’t be able to use it.

Without a trigger for crystal formation, motionless water molecules can remain in a liquid state below the normal freezing temperature of water. In this experiment, tap water freezes first since ice crystals often form on impurities in the water. Other ice crystals quickly form around the seed crystals, eventually freezing the entire bottle into solid ice.

In supercooled purified water, a crystal lattice of ice can also begin to form at the result of motion, or impact. Once crystal formation begins at a single spot, all of the other supercooled water molecules snap into formation, forming solid ice.

Try it! It may take more than one attempt for a great result, so freeze several bottles at a time.

Cornstarch Frescos

 - by KitchenPantryScientist

Want to get a taste of what it’s like to do a fresco painting?

Everyone from the ancient Minoans on the island of Crete, to Leonardo de Vinci, used this classic technique to paint into wet plaster made of lime, sand and clay. It was tricky, since you could only do a small area at a time, and the colors often got lighter as they dried.

Some frescos have lasted thousands of years as the result of the chemical reaction between the fresco materials and atmospheric carbon dioxide, which form calcium carbonate, the same material limestone is made of.

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We created this experiment using a cool, fun-to-play with false fresco material made with a mixture of cornstarch and water. To make it more science-y, you can make it with cornstarch and red cabbage juice (instead of water) in order to paint with acids and bases!

Remember, all chopping and boiling of red cabbage should be done with adult supervision. The pH fresco won’t stain your driveway, but depending on the food coloring you use, the painted fresco may leave marks on concrete. You can also do this in small, flat containers to contain the mess, or if you want to do it indoors.

You’ll need

– 16 oz Corn starch 

- scant 1 ½ red cabbage juice* for an acid/base fresco or scant 1 ½ cup water for painted fresco

- baking soda and vinegar for pH fresco

- food coloring for painted fresco

-toothpicks or small paintbrushes

*To make red cabbage juice, chop up ½ head of red cabbage, cover with water and boil for 10 minutes. Strain out cabbage.  More detailed instructions here.

 

Step 1:   Mix together the cornstarch and either water or red cabbage juice. The resulting mixture will look like glue. If it’s too dry and crumbly, just add a little more water until the consistency seems right. You should be able to roll it into a ball, but it should drip like a liquid when you stop moving it around.

Step 2.   Pour some cornstarch mixture onto a clean, flat spot on a driveway or sidewalk. Alternately, you can pour it into a tray or pie tin.

Step 3.    When the mixture has flattened out, let it sit for 5 or 10 minutes before you begin painting on it.

Step 4.     For an acid/base fresco made with red cabbage juice, put vinegar in one cup and a few tablespoons baking soda mixed with ¼ cup water in a second cup. Use toothpicks or paint brushes to make designs on the cornstarch with the vinegar (turns red cabbage cornstarch mix pink) and baking soda solution (turns red cabbage cornstarch mix blue.) You can also paint on this fresco with food coloring.

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Do acid/base painting with vinegar and baking soda on fresco made with cornstarch and red cabbage juice. KitchenPantryScientist.com.

For a painted fresco, put food coloring on a plate and use toothpicks or paintbrushes to paint designs on your fresco.

Paint your cornstarch and water fresco with food coloring. KitchenPantryScientist.com

Paint your cornstarch fresco with food coloring. KitchenPantryScientist.com

Step 5.   Let your frescos dry to see what happens to the colors.

Step 6.  Wash your frescos off the sidewalk using water from a hose.

The Science Behind the Fun:

The substance you made using water and cornstarch is called non-Newtonian, because it doesn’t act the way we expect a liquid to behave, and acts more like a solid if you stir it around or try to move it quickly.

When you use food coloring to paint on the cornstarch goo, the water-based pigments (color molecules) in the food coloring are absorbed into the cornstarch mixture, but they don’t travel diffuse very far since the cornstarch mixture is so thick. Here’s another diffusion experiment you can try called  Homemade Window Stickies.

Baking soda will turn cabbage juice pigment blue, while vinegar will turn it pink.

Baking soda will turn cabbage juice pigment blue, while vinegar will turn it pink.

If you try the acid/base painting, you’ll see that vinegar, an acid, makes pink lines and baking soda solution, a base, makes blue or green lines. The pigment from the red cabbage juice is an acid-base indicator that changes shape depending on pH, absorbing light differently and changing color.

 

Water Rocket Parachutes

 - by KitchenPantryScientist

For some serious outdoor fun, try a little rocket science and parachute engineering. Click here to watch a demo and segment on rockets I did for Kare11 Sunrise (the top video on the page is metamorphosis, the bottom one is rockets)!

NASA works hard designing new parachutes to slow the descent of spacecraft so they aren’t damaged when they land on distant planets. It can be tricky, since parachutes depend on air resistance to slow the descent of their loads, and many planets have very little atmosphere.

Here on Earth, you can design and test parachutes for our terrestrial atmosphere using produce bags, glue dots and string attached to a water rocket, to see what works best! Click here for detailed instructions on making a water rocket!

You’ll need a bike pump, an empty 1L plastic bottle, a cork that fits the bottle, cut in half, an inflation needle, lightweight plastic bags, like produce bags, string or twine, and glue dots (optional)

1. Make a water rocket. Directions for assembling the rocket are here: http://kitchenpantryscientist.com/simple-water-rockets/ 

2. Cut produce bags into large squares.

3. Cut 4 or more strings to attach the produce bag parachute to the rocket. You can use kitchen twine, yarn or embroidery thread.

Use glue dots to attach your parachute to strings.

Use glue dots to attach your parachute to strings.

4. Use glue dots to firmly  attach the strings to the plastic, and duct taping the parachutes onto 1 liter bottles. If you don’t have glue dots, punch holes in the corners of your parachute and tie the string on.

5. Securely attach the strings on your parachute to the bottom of the 1L bottle with duct tape.
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Safety goggles are required for this experiment!

6. Once you’ve made a parachute and attached it to a bottle, fill the bottle with 3-4 inches of water and plug it with a cork that’s been cut in half and impaled with a ball inflation needle.

Point the bottle away from you, with the cork down and the bottom up!

Point the bottle away from you, with the cork down and the bottom up!

7. Put on your safety goggles, attach the needle to a bike pump, set the bottle in a box or container so the bottom of the bottle is pointing up and away from you with the parachute positioned over the bottle (see photo), and start pumping!

What happens? As air pressure builds in the bottle, it pushes the cork and water down towards Earth, and sends the rocket in the opposite direction. Gravity pulls the empty bottle back to Earth, but the open parachute attached to it has a large surface area, which increases air resistance and adds a huge amount of drag to the falling rocket, slowing its fall. 

The shape of the parachute, the length of the strings, and even the material the parachute is made from all affect how air moves around it and how well it slows the fall of an object. Adding holes to the parachute to help control air movement can also affect how well it works. It may take several tries to get your parachute to work, so don’t get frustrated! Just keep re-engineering it!

Have fun rocketing!

Summer Changelings

 - by KitchenPantryScientist

Summer surrounds us with science. We’ve been catching tadpoles and capturing caterpillars and releasing them as frogs and butterflies. It’s nothing short of amazing to watch these creatures move through a process called metamorphosis, which changes them from one form to a completely different one as they become adults. This is a great survival tactic, since the youngsters and adults live in different areas and eat different things, so they’re not completing for food or space!

You can look for monarch caterpillars on milkweed and swamp milkweed, which you see in the video above. Bring plenty of food home for them to eat as they grow (the plants you found them on.) Tiger Swallowtail Caterpillars prefer a diet of dill! If you have trouble finding caterpillars, plant some milkweed and other butterfly-friendly flowers in your garden! The monarch population is in trouble due to lack of milkweed, which once grew everywhere. Click here for more information raising Monarchs.

Monarch caterpillar preparing to form a chrysalis

Monarch caterpillar preparing to form a chrysalis

 

Newly-formed Monarch butterfly chrysalis

Newly-formed Monarch butterfly chrysalis

We caught tadpoles in a local fountain (with permission, of course) and brought them home to observe. When they became tiny toads, we released them in the same fountain where we caught them. Before catching tadpoles, check local regulations to make sure it’s allowed and ALWAYS return them to the exact spot where you caught them, to avoid the spread of deadly fungi and invasive species! If you can’t return them to the same spot, don’t bring them home! Keep them in water from the source where you caught the them, and never add tap water to their habitat, since chlorine will kill them. Be sure there is a rock for them to crawl onto when they become frogs or toads. They’ll eat water plants and algae from their original habitat, but you can also boil green lettuce in bottled water and chop it finely to feed your tadpole. Release them immediately when they hop out of the water, since it may be difficult to know what to feed them once they’re mature.

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mature frog with nearly-mature tadpole in background

16 Summer Science Experiments

 - by KitchenPantryScientist

Between working on a follow-up to Kitchen Science Lab for Kids (which involves testing, writing up and photographing 52 experiments), driving my kids around to camps and sports, and doing science outreach at libraries, bookstores and on TV, I’m finding it hard to keep up. Here’s a short video on how to make tie-dye milk (a surface tension experiment), which I did on WCCO Mid Morning show last week and forgot to post!

Diet Coke Mentos fountain. Photo by http://www.amberprocaccini.com/

Diet Coke Mentos fountain. Photo by http://www.amberprocaccini.com/

Luckily, between all the camps and activities, the kids and I are having fun digging in the dirt, blowing giant bubbles, and watching tadpoles and monarch caterpillars go through metamorphosis!

What science experiments are you doing this summer? It’s a great time to take science outdoors!

Here are some of our favorites:

Got water? Make siphons, a water-purifier, water rockets, or fire-proof water balloons.

Hungry? Build a solar oven from a pizza box and bake s’mores.

Stand on eggs or throw them as hard as you can without breaking them. You can always clean up mistakes with your hose!

Play magician with the tablecloth trick, or make paper bag volcanoes erupt in your back yard.

Of course, there’s always the famous Mentos geyser, and film canister rockets are always a hit.

Nature walk bracelets add fun to any excursion, and you can collect water from trees or make water filters with grass and sand.

August is a great time to find Monarch caterpillars or study the earthworms in your back yard.

And no summer would be complete at our house without an epic marshmallow shooting competition. You’ll even learn some physics!

Soapy Science: Giant Bubbles

 - by KitchenPantryScientist

From surface tension to evaporation, science come into play every time you blow a bubble.

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Water molecules like to stick to each other , and scientists call this sticky, elastic tendency  “surface tension.” Soap molecules, have a hydrophobic (water-hating) end and (hydrophilic) a water-loving end and can lower the surface tension of water. When you blow a bubble, you create a thin film of water molecules sandwiched between two layers of soap  molecules, with their water-loving ends pointing toward the water, and their water-hating ends pointing out into the air.

As you might guess, the air pressure inside the elastic soapy sandwich layers of a bubble is slightly higher than the air pressure outside the bubble. Bubbles strive to be round, since the forces of surface tension rearrange their molecular structure to make them have the least amount of surface area possible, and of all three dimensional shapes, a sphere has the lowest surface area. Other forces, like your moving breath or a breeze can affect the shape of bubbles as well.

The thickness of the water/soap molecule is always changing slightly as the water layer evaporates, and light is hitting the soap layers from many angles, causing light waves to bounce around and interfere with each other, giving the bubble a multitude of colors.

Try making these giant bubbles at home this summer! They’re a blast! (It works best a day when it’s not too windy, and bubbles love humid days!)

To make your own giant bubble wand, you’ll need:

-Around 54 inches of cotton kitchen twine

-two sticks 1-3 feet long

-a metal washer

1. Tie string to the end of one stick.

2. Put a washer on the string and tie it to the end of the other stick so the washer is hanging in-between on around 36 inches of string. (See photo.) Tie remaining 18 inches of string to the end of the first stick. See photo!

This bubble wand is a little longer than 18 inches on a side.

This bubble wand is a little longer than 18 inches on a side.

For the bubbles:

-6 cups distilled or purified water

-1/2 cup cornstarch

-1 Tbs. baking powder

-1 Tbs. glycerine (Optional. Available at most pharmacies.)

-1/2 cup blue Dawn. The type of detergent can literally make or break your giant bubbles. Dawn Ultra (not concentrated) or Dawn Pro  are highly recommended. We used Dawn Ultra, which is available at Target.

1. Mix water and cornstarch. Add remaining ingredients and mix well without whipping up tiny bubbles. Use immediately, or stir again and use after an hour or so.

2. With the two sticks parallel and together, dip bubble wand into mixture, immersing all the string completely.

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3. Pull the string up out of the bubble mix and pull them apart slowly so that you form a string triangle with bubble in the middle.

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4. Move the wands or  blow bubbles with your breath. You can “close” the bubbles by moving the sticks together to close the gap between strings.

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What else could you try?

-Make another wand with longer or shorter string. How does it affect your bubbles?

-Try different recipes to see if you can improve the bubbles. Do other dish soaps work as well?

-Can you add scent to the bubbles, like vanilla or peppermint, or will it interfere with the surface tension?

-Can you figure out how to make a bubble inside another bubble?

 

 

 

 

The Cousteaus: Family with a Vision:

 - by KitchenPantryScientist

A few weeks ago, the kids and I were lucky enough to hear the Cousteau family speak at Beth El Synagogue as part of their Inspiring Minds Series. World-famous ocean researcher, conservationist and visionary Jacques Cousteau died in 1997, but his son Jean-Michel and his grandchildren are carrying on his legacy.

Jean-Michele was delightful, joking with his grown kids onstage even as he reminded us that there is only one water system on Earth and that we need to protect it. He worried out loud about what the future holds for our children, and told the story of walking down a beach to see a little boy return a piece of litter to an embarrassed adult with the words, “Excuse me sir, you dropped this!” His stories from the front lines of our struggling seas and polluted beaches reminded the audience that teaching conservation is most often a matter of “reaching the heart.” His PBS website Ocean Adventures” is filled with fantastic videos and activities for kids.

Celine Cousteau, who has a background in psychology, talked about living her life at split level, with “one eye above the water, but always happy to be pulled back to the ocean.” After first visiting the Brazilian Amazon when she was nine, she has returned every year and is currently working on a project called  “Tribes on the Edge,” to educate public on the struggles of the indigenous people there.
She says in one blog post, “Telling the stories of the indigenous people of the Vale do Javari is nothing short of complex- from the logistics and production, to the tribal politics, to the content. I could not have chosen a more challenging subject and location…but really, it chose me. They need to be heard and I can help make that happen. They want the world to know they exist and they matter. They don’t want to die from hepatitis, malaria, tuberculosis, or be contaminated by the invasion of oil companies or illegal activities. They want to choose their fate. Wouldn’t you?”

Fabien Cousteau talked about Mission 31, which documented Fabien and his team’s 31 day research stint in Aquarius, the world’s only underwater marine laboratory, located nine miles off the coast of the Florida Keys, and 63 feet beneath the sea. The researchers lived and worked underwater, and when they weren’t diving, they lived and worked in a space about the size of a school bus!

It was wonderful to hear stories from this adventuring family on a mission to remind us of our responsibilities as stewards of this planet (and of each other.) As a sometimes overprotective parent, it was also great to hear Celine, a mom herself, remind us to let our kids explore and go on some adventures of their own. After all, some day they’ll be the ones out saving the world.

Click here for an experiment you can do with kids to learn more about ocean acidification!

 

Nature Walk Bracelets

 - by KitchenPantryScientist
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Nature Walk Bracelets from “Kitchen Science Lab for Kids” Quarry Books

I can’t get over how young my kids look in this post, which I first published a few years ago. This is a great science/art crossover project and one of these bracelets would make a fantastic Mother’s Day gift! Just bring an extra bag along and pick up some extra flowers, petals, leaves and seeds for mom’s bracelet. You can assemble it when you get home. Just leave one edge leaf-free so you can put it on her wrist!
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Spring has finally arrived, and a fantastic way to enjoy it is to take a nature walk.  While you walk, watch for signs of spring and assemble your discoveries on your wrist with a nature walk bracelet.  It’s always a good idea to bring a few bags along too- one for larger treasures (like pine cones) and one for trash.  You can study nature and clean up the environment at the same time!

All you need is duct tape.  Cut the tape so it fits comfortably around your wrist and tape it around like a bracelet, sticky side out.  Take a walk in a park or down your own street and look for small leaves, acorns, flowers and other natural artifacts to adorn your wristlets.  Be sure to watch for birds while you walk! There are a number of great apps you can use to identify what species of plants you find, including Leafsnap!

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We wore our bracelets all afternoon and several people mistook them for real jewelry.  My oldest daughter thought they looked even prettier as the leaves and flowers wilted and flattened out on the tape.

IMG_2694Enjoy!

Fossil Hunting

 - by KitchenPantryScientist

Every fossil has a story to tell.

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Whether it’s the spectacular specimen of a dinosaur curled up on it’s eggs or a tiny Crinoid ring, mineralized remains offer us a snapshot of the past, telling us not only what creatures lived where, but about how they lived and the world they inhabited.

Growing up surrounded by the flat-topped, windswept Flint Hills of Kansas, it was hard to imagine that I was living in the bottom of an ancient seabed, but there was evidence of the Permian period all around.

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Now, when my kids and I return to my hometown, a fossil-hunting trip is always part of our routine, and we hunt for shells and coral where roads cut through crumbling limestone and and chert (flint.) Looking up at layer after layer of rock and shells, I can almost feel the weight of the water that once covered the land.

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An episode of RadioLab we heard on the drive North from Kansas to Minnesota explained that coral keeps time and that by comparing modern coral to ancient  coral fossils, scientists discovered that millions of years ago, years were about 40 days shorter than they are now. Can you guess why? Give the podcast a listen here. My mind was blown!

A visit to the Flint Hills Discovery Center in Manhattan, KS gave us more insight into the amazing geology, ecology and anthropology of the Flint Hills and the Konza Prairie that blankets them. Most people don’t know that the great tallgrass prairies of the United States wouldn’t exist if not for humans, who have been burning them for thousands of years.

What do you know about where you live? What’s it like now? What do you think it was like long, long ago? Are there fossils nearby?

Here are some fossil-hunting resources I found online, in case you want to go exploring:

http://geology.about.com/od/fossilbasics/tp/parks-that-allow-fossil-collecting.htm

http://mentalfloss.com/article/50997/10-states-fossil-hunting-sites-public

http://www.fossilsites.com/

http://www.fossilguy.com/sites/

http://www.fossils-facts-and-finds.com/fossil_hunting_usa.html