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.
From surface tension to evaporation, science come into play every time you blow a bubble. Here’s some bubble science, along with a recipe for making giant bubbles from my book Outdoor Science Lab for Kids!
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!
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.
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.
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.
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?
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.
To make a holidays version of the fizzing bath tablets in the video, we scented them with pumpkin pie spice and added a little more oil to incorporate the extra ingredients.
1 cup baking soda
¼ cup cream of tartar
3 Tbsp. coconut oil, melted to liquid
1 tsp. pumpkin spices
-Whisk together baking soda, cream of tartar and pumpkin spices. Slowly drizzle in coconut oil, mixing immediately. Stir for several minutes until you get a nice even mixture that holds together when you press it between your fingers. Add a little more oil if it is too powdery.
-Add a few drops of food coloring and mix again until the color is incorporated.
-Press the bath bomb mixture into a tablespoon and tap in on a tray to remove the bath tablet. If they don’t hold together, try adding a little more oil and mixing again. Dry the bath fizzies on a plate or cooking sheet and package them in cellophane bags or pretty baking cups for friends and family. Use the fizz bombs within a few weeks for maximum fizziness!
You can make larger “bath bombs” using molds for round ice cubes (which we found at Target.) Double or triple the recipes, gently press some mixture into each side of the mold, and mound a little extra on each side. Press the mold together to compress the bath bomb mixture into a single ball. Tap one side gently with the back of a spoon and gently open the mold to release that side of the sphere. Hold it in your palm and repeat with the other side to release the entire bath bomb from the mold.
The science behind the fun: The chemical name for baking soda is sodium bicarbonate , and cream of tartar is an acid called potassium bitartrate, or potassium hydrogen tartrate . When you mix them together in water, you create a chemical reaction that forms carbon dioxide gas bubbles! It’s interesting to note that at temperatures below 76 degrees F (25 C), coconut oil is a solid, but that at temperatures above this, it melts into a clear liquid. How does this affect your bath fizzies? Will they work in cold water as well as they do in warm water? Try it!
Eggs and sugar have great chemistry. Mix them together to create these sweet, crunch Halloween treats with a recipe from my upcoming book “Kitchen Science Lab for Kids: Edible Edition.“
They’ll take a few hours to bake, so plan ahead for this fun, edible science project.
Meringues are simply egg whites whipped into sugary foams. As you whip air into the mix, glue-like egg white proteins stick to the bubbles, stabilizing them to form a thick foam. The sugar you add combines with water from the eggs to form a sweet syrup.
When you bake meringue at a low temperature for a long period of time, the sugar and protein are transformed from an elastic goo to a glassy state, creating a crunch mouthful of bubbles.
Hard meringues are made using ¼ cup sugar per egg white, with a pinch of cream of tartar. Don’t skip the cream of tartar (an acid.) It helps stabilize the egg whites in the meringue.
To make Halloween Meringues, you’ll need:
3 egg whites from extra large eggs
1/8 tsp cream of tartar
¾ cup granulated sugar
1/4 tsp Vanilla
Food coloring (gel works best)
Sprinkles or dusting sugar (optional)
Stand mixer or hand mixer
2 baking sheets
Pastry bags or large plastic zipper bags with the corners cut off
Round piping tips for pastry bag, if you have them
1. Pre-heat oven to 200 degrees F.
2. Line two baking sheets with parchment paper.
3. Beat three egg whites on medium until they start to foam.
4. Add 1/8 tsp. cream of tartar and continue to beat the egg whites, increasing the speed to high.
5. When the foam gets thicker enough to form soft peaks, add 3/4 cup sugar, a tablespoon or so at a time as you beat the eggs. Add vanilla.
6. Continue beating the mixture until stiff, glossy peaks with rounded tips form. Don’t over-beat the meringue.
7. Add a round tip to the pastry or plastic bag. Fill the bag with the meringue you made.
8.Use the bag and tip to pipe half of the meringue into blobs. You can color it with food coloring before piping it, if you wish.
9. Make some colorful streaks on the meringues by using a toothpick to smear food coloring on the inside of the pastry tip before putting it in the bag and piping the meringue. A small tip can be used to create eyes for the blobs, snakes and worms, or you can use sprinkles and dusting sugar to decorate.
10. Bake the meringues for 1-2 hours, until they feel dry and let them cool.
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.
Hands-on science experiment books are a great way to ease kids back into creative learning!
I recently shared some of the fun, easy, inexpensive science project ideas from my two newest books, “STEAM Lab for Kids” and “Star Wars Maker Lab” with a group of teachers on Twin Cities Live. Check out the clip below to learn to make hoop gliders and grow gorgeous Epsom salt crystals!
You can find my books at your local library, or pick them up at your favorite online or bricks-and-mortar retailer!
Take your summer food game up a notch using… science! Sorbet recipe below. Vinaigrette recipe is in the post below this one.
Simple Freezer Strawberry Sorbet (adapted from Epicurious.com)
30 minutes hands-on prep time, 8 hours start to finish
*Parental supervision required for boiling sugar syrup
a shallow dish
1 quart strawberries
1/3 cup lemon juice
1/3 cup orange juice
1 cup sugar
2 cups water
What to do:
- Make a sugar syrup by bringing 1 cup sugar and 2 cups water to a boil in a heavy sauce pan. Boil for 5 minutes.
- Puree strawberries in a blender or food processor until smooth.
- Add strawberries, lemon juice and orange juice to the sugar syrup.
- Pour mixture into a shallow dish and cool for 2 hours in the refrigerator.
- Put the chilled sorbet mix in the freezer for 6 hours, stirring every hour.
- Enjoy your sorbet!
The Science Behind the Fun:
In sorbet, sugar acts as an antifreeze agent, physically getting in the way of ice crystal formation to keep crystals small, so that you don’t end up with one big chunk of ice. Pre-chilling the mixture before freezing it allows it to freeze faster, which also encourages smaller crystals to form.