Under the right conditions, purified water can get much colder than 32 degrees before it freezes into a solid. This “supercooled” water will instantly freeze when it touches an ice crystal.
You don’t need a special lab to make supercooled water. In fact, you can make it in your own freezer!
1. Place three 12 oz bottles of water (caps loosened and re-tightened) in the freezer. Two should be filled with purified water and one with tap water.
2. Wait 2 hours and then check them every 5 minutes. When the tap water is frozen, gently remove the other two bottles from the freezer. (Tap water freezes first, because it contains some impurities that help ice crystals form more easily.)
3. Carefully open one bottle of purified water and pour it onto a few ice cubes on a plate. The supercooled water from the bottle will instantly crystallize into ice when it hits the cubes, making slush. Try it with the second bottle. There may be some freezing time variation between freezers, so you may have to experiment to find the perfect amount of time it takes your freezer to supercool water!
You can do the same thing by putting bottled water in a cooler full of ice, salt, and water. Salt lowers the melting temperature of ice, which makes the salty ice water cold enough to freeze bottles of liquid. Try the same experiment using soda to make a slushy! (From Outdoor Science Lab for Kids-Quarry Books 2014)
Brrr. It’s really cold here in Minnesota. Perfect for making ice lanterns by filling balloons with water and setting them outside the back door. I had a great time talking ice lanterns and homemade ice cream (an edible experiment in my new book) on WCCO MidMorning this AM. As promised, here’s the recipe for “Ice Cream Keep Away.” After all, it’s never to cold to eat ice cream.
Ice Cream Keep Away (from Outdoor Science Lab for Kids- Quarry Books 2015)
- – 2 cups milk
- – 2 cups heavy cream
- – ½ cup sugar
- – 2 Tbs. vanilla
- – quart or pint-sized plastic zipper freezer bags
- – gallon-sized zipper freezer bags
- – 2 cups of rock salt or table salt
- -large bag of ice
- -dish towels
Safety Tips and Hints
- If the ice cream isn’t frozen when you check it, add more ice and salt to the outer bag and continue to throw it around for another five or ten minutes.
- You make enough ice cream mix in this lab to make 4 ice cream footballs at a time, so there’s plenty of ice cream and fun to go around!
Step 1: Make an ice cream mixture by combining 2 cups milk, 2 cups cream, ½ cup sugar and 2 Tbs. vanilla to a bowl and mix well.
Step 2. Add one cup of ice cream mixture to a quart or pint-sized freezer bag, squeeze out some of the air and zip it closed.
Step 3. Place the small bag of ice cream mixture in a second small bag, squeeze out the air and zip it closed as well.
Step 4. Place the double-bagged ice cream mixture into a gallon-sized bag and fill the larger back with ice.
Step 5. Pour a generous ½ cup of salt over the ice in the bag and zip the bag shut.
Step 6. Wrap a dish towel around the bag of ice and place it in a second gallon bag. Zip the outer bag closed.
Step 7. Play catch with the bag of ice and ice cream for ten or fifteen minutes.
Step 8. Remove the bag of ice cream mix from the outer bag and enjoy your frozen treat.
The Science Behind the Fun:
Making ice cream is a lesson in heat transfer and crystallization.
Water is the solid form of ice. When you add salt to ice, it lowers the freezing temperature of the water, melting it and allowing it to remain a liquid far below water’s normal freezing temperature of 32 degrees F (O degrees Celsius.)
In this lab, adding salt melts the ice, making a really, really cold ice-salt-water mix. The icy salt water pulls, or transfers, heat out of the ice cream mixture, freezing the water molecules in the milk and cream into ice crystals.
Depending on how fast ice cream freezes and what ingredients it contains, the ice crystals will be different sizes. If you freeze the mixture very fast, you will probably get big ice crystals that make the ice cream grainy. Ingredients like gelatin encourage smaller crystals to form, making smoother frozen treats. Adding emulsifiers like eggs to the mix helps the fats and water combine better, creating ice cream that thaws more slowly.
- Try added less salt to the ice to freeze the ice cream more slowly. How does this change the texture of the final product?
- What happens if you add a Tbs. of gelatin to the mix?
Repost from Dec.19th, 2010 (Photos from Kitchen Science Lab for Kids, Quarry Books 2014)
Have you ever gotten a shock from a doorknob after shuffling across a carpet? The term “static electricity” refers to the build-up of a positive or negative electrical charge on the surface of an object. In this case, the charged object is your body. You feel an electric shock as the charge you’ve collected from the carpet jumps from your hand to the metal doorknob.
Tiny particles called electrons have negative charges and can jump from object to object. When you rub a balloon on your hair, or a comb through it, many of these electrons are stripped from your hair and move to the balloon or comb giving it a negative charge (and often leaving your hair all positively charged and standing up as the strands try to avoid each other.)
The negatively charged balloon or comb then makes a great tool for making electrons jump around!
You can easily make a contraption called an electroscope using:
-some thin aluminum foil or mylar (the shiny stuff balloons and candy wrappers are made from)
-a balloon or comb.
- Cut the cardboard to fit over the mouth of the jar, poke the nail through the cardboard, tape on two long, thin strips of foil or mylar (see photo) and place the whole thing in the jar so the foil strips hang down, touching each other.
2. Charge your balloon or comb by rubbing it on your hair or clothing to give it a negative charge. Bring the charged object close to the nail head. You don’t even have to touch it!
What happened? Some negatively-charged electrons jump from the comb to the nail and into the strips of foil. The negative charge on the comb will push electrons (which are also negatively charged) down to the foil/mylar and give both strips a negative charge. The two strips try to move away from one another as the like charges repelled each other.
What happens when you make the strips out of different materials like paper? Are there other charged objects you can use to make your foil strips “dance”?
You can also bend a thin stream of water from the faucet by holding your charged comb next to it. The water is uncharged and is pulled toward the negative charge of the comb.
Try making small pieces of tissue paper float or dance by holding a charged comb or balloon next to them! We filled an empty soda bottle with tiny pieces of foil and made them jump around with a charged comb held close to the bottle.
Love basketball? Think you’re pretty good? Try taping some coins to a basketball, or covering one eye and shooting the ball. The coins change the ball’s center of mass, making it harder to shoot, and covering one eye messes with your depth perception! Try it!
I had fun thinking up these new basketball experiments that we tested on TV this week. Can you come up with one of your own? What could you try?
Get ready to make some noise! Read on to find instructions for making two simple experiments.
The sound we hear every day is energy that travels through air molecules as vibrations. In fact, you can’t hear sound in outer space, since there’s no air.
When I play my trombone, air travels from my lungs to my buzzing lips, which make vibrations inside the horn. The vibrations travel through the trombone, and the tube the vibration travel through gets longer when I extended the slide, making the sound lower. My daughter plays the violin, which, like other string instruments, can make short sounds by plucking the strings or a continuous sound with a bow that keeps them vibrating. Shortening the strings by pressing them down makes the pitch higher as the string vibrated faster.
We have a “drum” in our ears called an eardrum, or tympanic membrane that picks up sound vibrations in the air and transfers those vibrations to tiny bones in the middle ear, which then move them on to our inner ear, sending a message to our brain.
You can make a model “eardrum” out of a cup, saran wrap and sugar sprinkles that jump when you make a loud noise right next to it.
It’s also fun to make two simple musical instruments: a straw “clarinet” and a kazoo from a comb and tissue paper. Use the instruments to make the sugar crystals on a model eardrum jump around!
Click on this link to learn how to make straw “clarinets.”
To make comb kazoos, fold a piece of tissue paper in half the long way (see photo), place it over a comb with the teeth towards the fold, and place your lips on the tissue paper. Sing doo doo doo doo into the paper (don’t blow.) The vibrations from your voice will make the thin paper vibrate and buzz. It will tickle if you’re doing it right!
Use science to make your holidays shine! Here are a few fun ornaments adapted from projects in my book “STEAM Lab for Kids.” Basic instructions can be found below. Buy your own copy of “STEAM Lab for Kids” anywhere books are sold to learn more about the “Science Behind the Fun!” Happy Holidays!
LED Ornaments and Jar Globes:
To make LED ornaments, buy plastic jars or ornaments with removable bases. Use sculpting clay (the kind that won’t harden) to design a scene and add LEDs connected to a coin-cell battery to light your creation. LEDs can be ordered online. See images below.
Epsom Salt Crystal Ornaments:
(Warning: Hot liquids require adult supervision.) To make the Epsom Salt crystals, dissolve 3 cups of Epsom salts in 2 cups of water by heating and stirring until no more crystals are visible. This creates a supersaturated solution. Allow the solution to cool slightly. Hang pipe cleaners formed into snowflakes in jars or hollow ornaments and pour the solution in. When long, needle-like crystals have formed, remove the pipe cleaners from the jars. You can leave them in the ornaments, and drain the liquid.
With a few simple technology and art supplies, you can put together a simple kit that lets kids design and build bristle bots, art bots and light-up creatures.
The Science Behind the Fun: Hooking an unbalanced spinning toy motor to a brush sends vibrations through the bristles. The vibrating bristles move the brush, and anything attached to it, around on a flat surface. Make a disc robot by attaching toothbrushes to a CD and attaching a motor, or make a drawing robot with legs made of pens.
I’ve included ideas for items to put in a kit, along with a tech supply list and photos of the robots from STEAM Lab for Kids. Use your imagination for art supplies! Pair the kit with a book, like STEAM Lab for Kids (Amazon.com), which has instructions for making bristle bots, art bots and light-up creatures, or let tech-savvy kids take the reigns and start building!
LEDs, alligator clip test leads, toy motors and batteries let kids assemble simple circuits. (Supply list below photo)
Basic 3mm and 5mm through-hole LEDs (Art Bot, CD Bot, Light-Up Creature)
Small alligator clip test leads (Art Bot, CD Bot, Light-Up Creature)
AA battery holders (Art Bot, CD Bot )
AA batteries and 9V batteries (Art Bot, CD Bot )
9V battery clip snap-on connectors (battery snaps)
3V coin cell batteries (Light-Up Creature)
Mini electric motor for DIY toys (1500 rpm) for Art Bot, CD Bot
(Find these supplies at your favorite bricks and mortar location, like Axman Surplus stores, or get them online at Amazon.com or another tech retailer.)
Paper and plastic cups, brushes, toothbrushes, duct tape, zip-ties, and CDs all make great building supplies, and a glue gun always comes in handy.
Use your imagination for the art supplies.
And if you’ve got a kid who likes to sew, it’s fun to add supplies to make sewable circuits!
Sewable electronics: coin cell battery holders, sewable LEDs, snaps and conductive thread
Here are instructions for building a simple bristle bot.
Sound waves are formed when air molecules are compressed (pushed together), creating pressure waves.
It’s fun and easy to play with sound waves! Here are some ideas for you:
Have fun experimenting!
Combine science and art to engineer and decorate a custom water bottle jacket as unique as you are. Test different every-day insulators to see what works best to to keep water cold all day long!
-a washable plastic water bottle
-flexible insulating material, like craft foam, bubble wrap or fabric batting
-decorating materials, like stickers, ribbons or foam stickies
-a thermometer (optional)
-4 disposable empty water bottles or cans that are the same size (optional)
What to do:
(Optional) Test insulators by insulating each of the empty cans or bottles with different material. Fill each of them with the same amount of hot tap water and check the temperature of each periodically to see which material does the best job of slowing cooling of the water. The one that keeps water hot the longest is the best insulator, since it slows the movement of heat from one area to another.
Use the best insulator to build an insulating case for your water bottle. Make it big enough so that your bottle will slide out for washing. We used thick craft foam and covered it with adhesive craft foam. Shipping folders made of bubble wrap work well too! Here’s how we built ours…
Add some ice water to the bottle and you’re good to go! Just remove the jacket when you wash the bottle.
Robots took over the driveway last summer when we were photographing my new book “STEAM Lab for Kids: 52 Creative Hands-On Projects for Exploring Science, Technology, Engineering, Art and Math”
With a few supplies from your junk drawer and a few inexpensive tech supplies available online, kids can easily make their own CD Bots! Grab a copy of “STEAM Lab for Kids” for easy instructions, or figure out how to do it yourself by attaching a toy motor (connected to a battery) to a CD with toothbrushes glued to the bottom!