“When I wasn’t at school, I was experimenting at home, and became a bit of a Mad Scientist. I did hours of research on mayonnaise, for instance, and although no one seemed to care about it, I thought it was utterly fascinating. When the weather turned cold, the mayo suddenly became a terrible struggle, because the emulsion kept separating, and it wouldn’t behave when there was a change in the olive oil or the room temperature. I finally got the upper hand by going back to the beginning of the process, studying each step scientifically, and writing it all down. By the end of my research, I believe, I had written more on the subject of mayonnaise than anyone in history. I made so much mayonnaise that Paul and I could hardly bear to eat it anymore, and I took to dumping my test batches down the toilet. What a shame. But in this way I had finally discovered a foolproof recipe, which was a glory.” Julia Child, from My Life in France
Julia’s secret for fool-proof mayo? Beat the mixture over a bowl of hot water to get the oil and eggs to form an emulsion, which is a mixture of two thing which are normally immiscible, like water and oil. In an emulsion, a bunch of one type of molecule will actually surround individuals or small groups of the other type of molecule (think ring-around the rosy with one or two people in the middle who would rather not be there.)
When you’re trying to make an emulsion, it also helps to add a mediator called a surfactant to get between and interact with the immiscible molecules to stabilize the mixture. In a vinaigrette prepared using oil, mustard and vinegar, the proteins in the mustard act as surfactants.
To make delicious vinaigrette:
- Using a fork or wire whisk, mix together: 1 Tbsp. vinegar and 1 Tbsp. mustard.
- Add 3 Tbsp. oil (olive, vegetable or your favorite), drop-by-drop, whisking until you see an emulsion form! You can tell when an emulsion begins to form, because the mixture will start to look lighter-colored and thicker as the molecules are rearranged and reflect light differently!
Try some variations on these kitchen experiments. Does it work better to use a cold egg, room temperature egg, or warm egg? What happens if you try to make mayo by setting your mixing bowl in a bowl of ICE water? Do you get an emulsion?
When whipping up mayonnaise, adding a little water to the eggs before adding the oil helps make some of the proteins in the eggs more available to act as surfactants. Of course, adding a little mustard helps too and tastes great!
Here’s the New York Times recipe we used to make mayonnaise:
- 1 large egg yolk, at room temperature
- 2 teaspoons lemon juice
- 1 teaspoon Dijon mustard
- 1/4 teaspoon kosher salt
- 1 teaspoon cold water
- 3/4 cup neutral oil such as safflower or canola
- In a medium bowl, whisk together the egg yolk, lemon juice, mustard, salt and 1 teaspoon cold water until frothy. Whisking constantly, slowly dribble in the oil until mayonnaise is thick and oil is incorporated. When the mayonnaise emulsifies and starts to thicken, you can add the oil in a thin stream, instead of drop by drop.
As Julia Child would say, “Bon Appetit!”
Looking for fun, creative summer projects? I showed off some projects from STEAM Lab for Kids this morning on WCCO MidMorning!
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!
I took some behind-the-scenes video when we were photographing my new book “STEAM Lab for Kids” last summer. Here’s a fun engineering project from the book! #summer #fun #balloon #rockets #STEAM #STEM
Happy Saint Patrick’s Day! Yesterday, I demonstrated some fun rainbow science on The Jason Show. Click here to watch!
As part of the segment, I featured the “Rainbow Slime” experiment from my new book, “STEAM Lab for Kids,” which you can order from Amazon, Barnes and Noble, or your favorite online retailer. Here’s a sneak-peek at a few photos from the book.
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)
Grab your coat and head outside to try this fun winter science project!
A large plastic zipper bag
Cotton kitchen twine
a toothpick or wooden skewer
a spray bottle
a squeeze bottle or syringe (optional, but helpful)
a very cold day (below 10 degrees F works best, but you can try it on any day when it’s below freezing)
Note: This experiment takes lots of playing around and results will vary depending on how cold it is outside. Remind your kids (and yourself) to be patient and try it on a colder day if it doesn’t work the first time around! If the bag leaks too quickly, try making one with smaller holes around the string.
What to do:
- Use a toothpick or skewer to poke 3 small holes in the bottom of a zipper plastic bag. Make one in the middle and one on each end.
- Cut three long (3 feet or so) pieces of kitchen twine and knot them at one end.
- Carefully thread the twine through the holes in the bag so that the knots are inside the bag to keep the strings from falling through. Try to keep the holes from getting too big, since the bag will be filled with water and you’ll want it to drip out very slowly around the string.
4. Attach two more pieces of twine to each top corner of the bag (above the zipper) to use for hanging the bag
5. Go outside and hang the bag from a low tree branch or railing.
6. Tie each of the three strings to something on the ground, like a rock, piece of wood, or the handle of an empty milk carton filled with water to weight it down. Arrange the objects so that the strings loosely radiate out at around a 45 degree angle. (See photo)
7. Add food coloring to some ice-cold water in a pitcher.
8. Fill the spray bottle with ice-cold water.
9. Add the cold colorful water to the zipper bag hanging outside. Zip the top of the back to slow the rate of leaking.
10. Immediately spray the strings with water to guide the leaking water down the strings.
10. Wait for the water on the strings to freeze. Use your syringe to add a little bit more water to the strings (same color) and wait for them to freeze again. Repeat until you have a nice layer of ice/icicles.
11. Refill the bag, using a different color of ice-cold water. Spray the strings lightly again. Repeat step 11.
12. Add layers of color to the icicles until you’re happy with the way they look!
The science behind the fun:
Icicles form when dripping water starts to freeze. Scientists have discovered that the tips of icicles are the coldest part, so that water moving down icicles freezes onto the ends, forming the long spikes you’ve seen if you live in a cold climate. When you add different colors of water to icicles in sequence, the color you add last will freeze onto the tip of the ice.
You’ll find more fun ice science experiments in my book “Outdoor Science Lab for Kids” and in my upcoming books “STEAM Lab for Kids” (Quarry Books April 2018) and “Star Wars Maker Lab” (DK- July 2018)
Have you ever wondered why putting chemicals like salt on a road makes the ice melt?
To see how NaCl (table salt) melts ice by lowers the melting temperature of water, you’ll need an ice cube, a glass of water, and a piece of kitchen twine or string about 6 inches long and salt.
What to do:
Drop an ice cube in a glass of ice water. Try to pick the ice cube up without your fingers by simply placing the string on it and pulling up. Impossible, right?
Now, dip the string in water, lay it across the ice cube and sprinkle a generous amount of salt over the string/ice cube. Wait about a minute and try again to lift the cube using only the string. What happens?
It may seem like magic, but it’s only science. Here’s a video from my KidScience app where I demonstrate the experiment.
Salt lowers the temperature at which ice can melt and water can freeze. Usually, ice melts and water freezes at 32 degrees Farenheit, but if you add salt to it, ice will melt at a lower (colder) temperature.
The salt helps the ice surrounding the string start to melt, and it takes heat from the surrounding water, which then re-freezes around the string.
Different chemicals change the freezing point of water differently. Salt can thaw ice at 15 degrees F, but at 0 degrees F, it won’t do anything. Other de-icing chemicals they add to roads can work at much colder temperatures (down to 20 degrees below zero.) If it’s cold enough, even chemicals won’t melt the ice.
Pressure can also make ice melt at colder temperatures. This is why ice skates glide on rinks. The pressure is constantly melting the ice a where the blade presses down on it so the blade glides on a thin layer of water!
There are few gifts more fun than a homemade science kit. Give a kid a bottle of vinegar and a box of baking soda and you’ll make their day. Throw in a bottle of Diet Coke and some Mentos mints, and you may be their favorite person ever. Make a kit for your kids or grand kids. Make one for your favorite niece or nephew. Encourage kids to make kits for friends and siblings.
Here are some ideas for items to include in your kit.I’ve highlighted links to the experiments on my website (just click on the blue experiment name) in case you want to print out directions to add to your kit. You can also find these experiments on my Kitchen Pantry Scientist YouTube channel!
-composition book: Makes a great science notebook to draw, record, and tape photos of experiments into.
-clear plastic cups to use as test tubes and beakers
-measuring spoons and cups
-school glue (white or clear) for making Mad Scientist’s Slime
-contact lens solution for making Borax-free Slime
-gummy worms to transform into Frankenworms
-baking soda: Can be used for a number of experiments like fizzy balloons, magic potion . Or just mix with vinegar to make carbon dioxide bubbles.
-vinegar Great for fizzy balloons , alien monster eggs and magic potion.
-balloons for fizzy balloons.
-dry yeast for yeast balloons.
-white coffee filters: can be used for magic marker chromatography, in place of a paper bag for a coffee-filter volcano or making red cabbage litmus paper.
-cornstarch:Lets you play with Cornstarch Goo, a non-newtonian fluid. Here’s the video.
-marshmallows with rubber bands and prescription bottle rings you have around the house can be used to make marshmallow catapults. My kids used theirs to make their own Angry Birds game.
-Knox gelatin and beef bouillon cubes can be used to make petri plates for culturing microbes from around the house. You can also use the gelatin for cool osmosis experiments!
-food coloring Helps you learn about surface tension by making Tie Dye Milk. Here’s the video. You can also easily make colorful sugar-water gradients that illustrate liquid density!
-Mentos mints will make a Mentos geyser when combined with a 2L bottle of Diet Coke.
-drinking straws are great for NASA soda straw rockets and a carbon dioxide experiment.
To take it up a notch, throw in a copy of one of my book! You can find them on Amazon, Barnes and Noble and anywhere else books are sold!
Crying over broken candy canes? Cry no more. Make art!
My publisher recently sent me a copy of “Amazing (Mostly) Edible Science,” by Andrew Schloss. There are tons of fun experiments in the book, but Candy Cane Origami seemed like a perfect one to try during the holidays.
*Melted candy can get dangerously hot, so parental supervision is required!
-candy canes (broken or whole), wrappers removed
-heavy-duty aluminum foil
-a cookie sheet
-a wire cooling rack
What to do:
- Preheat oven to 250F.
- Cover cookie sheet with foil
- Place candy canes on foil, not touching each other
- Bake candy canes for around 10 minutes and have an adult check them. They should be stretchy, but not too hot to touch.
- When the candy canes are ready, bend, fold, twist and pull them into cool shapes. Try pulling one long and wrapping it around a chopstick to make a spiral. What else could you try?
- If the candy gets to brittle to work with, put it back in the oven for a few minutes to make it soft again.
The science behind the fun:
If you looks at the ingredients of candy canes, they’re usually made of table sugar (sucrose), corn syrup, flavoring, and food coloring. Glucose and fructose are sweet-tasting molecules that stick together to make up most of the sugars we eat, like table sugar (sucrose) and corn syrup. You can think of them as the building blocks of candy.
At room temperature, candy canes are hard and brittle, but adding heat changes the way the molecules behave. Both table sugar and corn syrup contain linked molecules of glucose and fructose, but corn syrup has much more fructose than glucose, and the fructose interferes with sugar crystal formation. According to Andrew Schloss, “the corn syrup has more fructose, which means the sugar crystals in the candy don’t fit tightly together. The crystals have space between them, which allows them to bend and move without cracking.”
Here’s a great article on the science of candy-making!
If you’re looking for holiday gifts for a science-loving kid, my books Kitchen Science Lab for Kids and Outdoor Science Lab for Kids include over 100 fun family-friendly experiments! They’re available wherever books are sold.