Here’s a great project for pre-K kids. They can cut the fish out of paper or foam, pour the water and put a drop of soap behind the fish to make it “zoom.”
My original post and written directions for zooming fish can be found by clicking here.
If you’ve done an experiment where you drip water onto a penny, or made Tie Dye Milk, you know what surface tension looks like here on Earth. How does it look in space?
Here’s an amazing video demonstrating how the surface tension of water looks in zero gravity on the international space station. Fascinating!
Here are some of our favorite environmental science experiments. Click on the experiment name for directions and photos. I’ll post a new photosynthesis experiment on Monday!
Window Sprouts: Plant a bean in a plastic baggie with a damp paper towel to see how plants need only water and air to sprout roots and leaves. Here’s a short video demonstrating how to make a window garden.
Homemade Solar Oven: Using a pizza box, aluminum foil, plastic wrap, and newspaper, you can harness the sun’s energy to cook your own S’mores!
Nature Walk Bracelets: Wrap some duct tape around your wrist (inside out) and take a walk, sticking interesting natural objects like leaves and flowers to your bracelet. It’s a great way to get outdoors and engage with nature!
Carbon Dioxide and Ocean Acidity: See for yourself how the carbon dioxide in your own breath can make a water-based solution more acidic. It’s the same reason too much carbon dioxide in Earth’s atmosphere can be bad for our oceans.
Plant Transpiration: See how trees “sweat” in this survival science experiment.
Greenhouse Effect Experiment: With a few jars, plastic bags, ice, and a thermometer, you can demonstrate how greenhouse gases can trap heat in our atmosphere.
Earthworm Experiment: Do you know what kind of earthworms are living in your back yard?
Composting: Be a composting detective. Bury some things in your back yard (away from power cables) and dig them up in a few months to see how they look. Composting reduces methane gas emissions (a greenhouse gas) from dumps.
Diffusion and Osmosis: See for yourself how the chemicals we add to water, put on our streets to melt ice, and spray on our lawns and crops can move into our soil, ground water, rivers, lakes and oceans.
Solar Water Purification: This project illustrates the greenhouse effect and is a fun “survival science” experiment. Requires hot sun and some patience!
Citizen Science: Don’t forget about all the real environmental research projects you can participate in through Citizen Science programs all around the world!
For mores activities and games, check out NASA’s Climate Kids website, to see a kid-friendly diagram of the water cycle, click here, or just get outside and enjoy the beautiful planet that sustains and nurtures us.
You can’t judge an egg by its shell, but you can use science to figure out whether or not it’s fresh.
Imagine an egg. It can be white or brown, since they’re identical except for shell color. There are two membranes inside an eggshell, separating it from the inside of the egg and helping to keep it safe from microbial invaders.
Under the membranes is the egg white, made up of proteins and water, and the yolk, which also contains fat and is enclosed in a sac. Tiny rope-like structures anchor the yolk between either end of the egg. The egg white contains a substance called lysosyme, which is a potent antibacterial. Eleven percent of an egg’s weight is made up by shell, 58% by white and 31% by yolk.
When a hen first lays an egg, the raw egg white contains carbon dioxide, making it look cloudy, and the proteins in the egg white are freshly folded into their correct protein shapes, so it will hold a nice shape in a pan. However, egg shells contain thousands of tiny pores, some big enough to see with the naked eye, and as an egg sits, it changes.
The contents begin to slowly shrink, and a small air pocket forms between the two membranes, usually at the large end. The egg’s pH, about 7.6 when first laid, rises as the egg ages and loses carbon dioxide. In just a few days, the pH may reach 9.7, causing the egg white to look clear and spread out more in a pan when the egg is broken.
The nicer shape and centered yolk of fresh eggs is why they’re recommended for frying. But why are older eggs better for boiling, and why does the yolk turn green sometimes?
Fresh eggs are harder to peel. When you boil an egg, it cooks from the outside to the inside, and its proteins become unfolded, or denatured. The denatured proteins are more likely to stick to the membranes on the eggshell of a fresh egg because the pH is lower. According to “FOODS, A Scientific Approach” by Charley and Weaver, eggs are easier to peel if their pH is greater than 8.7. In other words, old eggs that have lost carbon dioxide have a higher pH (are less acidic) and are easier to peel.
Sometimes, when you boil eggs, you see a greenish/gray/blue layer on the outside of the yolk. It’s the harmless product of a chemical reaction between the iron in the egg yolk and sulfer-containing proteins in the white. You can try to avoid it by using fresh eggs, using hot (not boiling water) to cook the eggs, by plunging eggs into ice water immediately after cooking, and by promptly removing the shells.
If you’ve heard of candling eggs, it involves shining a strong light through a raw egg to look at yolk position, air sac size and white clarity. You can also tell that an egg is older if it floats in water, due to the enlarged air sac.
Ideally, to cook perfect hard boiled (large) eggs, you put them in cold water, bring the water to a boil, remove the heat and let the pan stand with the lid on for 17 minutes before removing the eggs and plunging them into cold water. Alternately, boil large eggs for eleven minutes and put them in ice water to stop the cooking. For perfect eggs, prick the large end of your eggs with a pin to release the air in the air sac.
Between basketball games and homework this weekend, we stood barefoot on cartons of raw eggs and painted hard boiled ones with lemon juice and baking soda.
Why the eggfest? We’re making videos for some April KidScience app experiments!
Here are a few still shots of our lovely creations:
Whether you’re home or away, science can make any vacation more fun. You can collect data for real citizen science research projects by searching SciStarter.com or do your own experiments. KidScience app, based on the science projects on this website, puts fun science experiments at your fingertips on your iPhone, iPod Touch or iPad, no matter where you are.
I showed Kare11 viewers three of our favorite KidScience experiments: Red Cabbage Litmus Paper, Fizzy Balloons and Marshmallow Slingshots (using stuffed animals like Angry Birds to learn a little about the conservation of energy. Click here to watch the TV segment.
How will you mix a little science into your spring break?
“Are you a good cook?” was the first thing Dr. Tsneo Suzuki asked when I sat down in the office next to his cancer research lab at the University of Kansas. I stared at the picture of his wife, who I later learned had passed away from breast cancer, and wondered whether I should be offended.
After all, I was in my twenties and had five years of molecular biology experience under my belt. But I understood why he asked the question. Once you figure out how to test a hypothesis, most science experiments involve following recipes, which scientists call protocols. Generally, if you can read directions and mix things together in the correct order, in the right proportions, you can do things like amplify DNA and clone genes into bacteria.
So I truthfully answered “Yes, I’m a pretty good cook,” and got the job.
Food preparation is like a science experiment. If you can follow a recipe, you should get something close to what you set out to make, because often the ingredients will interact with each other to make something new. This is the very definition of a chemical reaction. Everything you cook with, from water to baking soda, is just a collection of molecules.
Here’s a collection of some food science experiments on my website. Since I love to cook, I hope to add more in the future! Leave a comment if you have other favorite kitchen science experiments, and I’ll try to add them to the list.
Testing Foods for Starch- Add a drop of iodine and watch for color change to detect starch.
Crock Pot Microbiology: Making yogurt from scratch is a delicious experiment
Yeast Experiment: Pyramids, Pasteur and Plastic Baggies- Grow yeast in a plastic bag to see how they make bread rise.
Emulsions: Mayonnaise and Vinaigrette- Mix the un-mixable using surfactants.
Curds and Whey: Make glue and plastic from milk and vinegar.
Gluten Ball- Explore the protein that makes bread chewy.
Red Cabbage Juice CO2 experiment- Use the pH-sensitive pigment in red cabbage to illustrate how CO2 can acidify liquids (and why soda is bad for your teeth.)
Homemade Petri Plates: test surfaces around your kitchen and house for microbes. Use to test fingers before washing, after washing with water alone, after washing with soap, and after using hand sanitizer.
So remember, cooking can make you a better scientist, and doing science can make you a better cook.
“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. In 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!
You can tell when an emulsion begins to form, because your mayo or vinaigrette will start to look lighter-colored and thicker as the molecules are rearranged and reflect light differently!
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.
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?
As Julia Child would say, “Bon Appetit!”
Today, I went into my daughter’s first grade classroom to do the famous volcano experiment that involves mixing baking soda (sodium bicarbonate) and vinegar (acetic acid). Unfortunately, with our hectic schedule there was no time to create a “work of art” volcano from paper mache or clay. So, we made one out of a paper bag. It was a smashing success.
To make your own paper bag volcano, you’ll need a brown paper lunch sack (or a slightly bigger one like we used), an empty plastic water or soda bottle, a cup of vinegar, red food coloring and about a fourth of a cup of baking soda.
Remove the lid from the bottle, invert the brown bag over it, and tear open the bottom of the bag, along the flaps. Then, loosely tape the paper sack so that it fits around the mouth of the bottle. Don’t tape it to the bottle. If you like to draw, you can decorate the bag with markers.. We squashed and tore the bottom of the bag a little, to make it look more mountain-like.
Now, remove the bottle, fill it with the vinegar and add several drops of red food coloring for your “lava.” Place the bag bag over the bottle to hide the lava container.
Place the volcano on a tray or something that will contain overflow and you’re ready for eruption!
Using a folded piece of paper, quickly dump all of the baking soda into your bottle to start the chemical reaction. You’ll see the volcano erupt as the baking soda combines with the vinegar to produce carbon dioxide gas, which is one of the gases spewed by real volcanoes.
If you liked this experiment, try making “fizzy balloons“ with the same ingredients (plus a balloon, of course!) If you want to learn more about carbon dioxide gas and the carbon cycle, here’s a link to a cool video from NASA that explains it using a banana and a chunk of coal.
Salt lowers the melting/freezing temperature of ice, which is the solid form of water. Here’s a fun experiment you can do to see for yourself how Sodium Chloride (table salt) makes ice melt and water refreeze on a string, allowing you to “magically” lift an ice cube from a glass of water.
Click here for detailed instructions and more about the science.
This video will soon appear on KidScience app‘s Premium version, which allows you to easily search for experiments and videos based on kids’ ages, type of science, what you have on hand, or how much time you have.