Category Archives: Science Experiments

Density in Action: Can You Sink a Marshmallow?

By Loralee Leavitt, Candy Experiments

At the USA Science and Engineering Festival in Washington, DC, children crowd around the Candy Experiments booth.  A volunteer asks if they’re ready to take the marshmallow challenge: “Can you sink a marshmallow?”

As Steve Spangler teaches in the lemon and lime sink-and-float experiment, an object sinks if it is more dense than water.  It floats if it is less dense than water.

When you drop a marshmallow in water, it floats like a balloon.  A marshmallow is full of air bubbles, which puff it out.  The sugar in the marshmallow gets spread out over a large area, making the marshmallow less dense than water.  So how do you make a marshmallow denser?  You have to make it smaller.

To try the marshmallow challenge, take a mini marshmallow and squash it.  You can do this by smashing it between your palms, rolling it between your fingers, or smashing it against a flat surface.  Try to roll it into a ball rather than flatten it into a pancake, because a pancake shape floats better than a ball.

When your marshmallow is as small as you can make it, drop it in water.  Does it sink?  If it does, you’ve made it denser than water.  You beat the marshmallow challenge!

If that was too easy, try a harder challenge: sinking a regular marshmallow.  Squash or roll it on a cornstarch-covered cutting board to keep it from getting too sticky. (Otherwise, you may have to scrape the marshmallow goo off your hands with a spoon.)  Then drop it in a water to see what happens.  You can also try this experiment with Peeps, 3 Musketeers, or other kinds of candy that float.



Loralee Leavitt destroys candy for the sake of science at Her new book, Candy Experiments, contains dozens of amazing experiments including creating giant gummi worms, turning M&Ms into comets, and growing candy crystals.  Candy Experiments is available at

The Invisible Secret Message That Glows in the Dark

Reveal invisible secret messages and drawings under a black light with a spooky homemade Halloween projector.

These handheld projectors are perfect for puppet shows, lighting up while trick or treating, flashing messages in the dark to your friends, haunted houses and more. Take them outside for fun after dark. Decorate a piece of paper, draw your message or picture with a fluorescent highlighter, glue it to a cup, add a black light and you are ready to take on the night.

With the Black Light Secret Message experiment, you’ll see that certain highlighters aren’t just brightly-colored – they’re actually fluorescent and glow underneath a black light! The secret messages and floating images you’ll create with this experiment are sure to create screams of joy and shrieks of excitement. Some even break open highlighters and squeeze out the ink to make glowing potions. On Friday, we will share the Science Behind some of our favorite glowing recipes.

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Instant Ice – Super Cold Water Turns to Ice Before Your Eyes

We recently came across this video by‘s reader Phil Sabine making its rounds on the Internet. In the video, Sabine takes a cold bottle of water, turns it upside down and then taps the bottom. The water instantly begins freezing from the bottom down to the top.

Is it magic? A slight of hand? Or did he switch the liquid in the bottle to something other than water?

The answer to all of the questions is no, there is no trick. The solution lies in the science behind the freezing temperature of water and how ice crystals form. This is also referred to as Supercooled Water.

Everyone knows the freezing temperature of water is 32 degrees Fahrenheit or 0 degrees Celsius. When this temperature is reached, the water molecules freeze by forming ice crystals. It’s easier for the water molecules to turn to ice on top of already formed crystals.  Ice crystals build on existing ice crystals to eventually freeze the entire bottle of water.

What starts the freezing ice crystal process? 

The process of starting the ice crystals is called “nucleation.” This starts from an impurity or scratch or piece of dust on the container holding the water. In this case, the water bottle. One ice crystal attaches to the imperfection, and the others grow on top.

What if the water bottle does not have an imperfection or impurity? Nucleation cannot begin, and the water stays in its liquid state. Even in temperatures below the freezing point. This state is called “metastable.” The water stays liquid until something kicks off the nucleation process.

In the SooCool video, Phil turns the bottle upside down and smacks it. This is enough to start the ice crystals to form and build on top of each other as they freeze down the bottle.

The water in the bottle isn’t frozen solid, but more slushy.

For an experiment, take a case of water and place it in the freezer. Keep all of the bottles in the same position and try not to make any dents or flaws in the plastic. Wait overnight and check the water. Some of the bottles may still be liquid. If this is the case, try different techniques of shaking, hitting or disturbing the water in the bottle to see if the water will instantly freeze.

Instant Freeze Soda

Did you know soda will also instantly freeze? Here’s a video of Steve demonstrating this on 9News. You can also read step by step directions and the science behind the Instant Freeze Soda on the experiment page.

Becky's Ink and Fire Extinguisher Surprise

Becky Ditchfield never wants to know what we’re doing for our Science Mondays segment on KUSA-TV 9News. This was our last segment of the year and I wanted to make it one for her to remember. I pulled out an old favorite from the Spangler repertoire, but it was new to Becky. In anticipation of your next question, here’s the disappearing ink recipe.

The Fear of Becoming Invisible – How Great Teachers Use Science Demos as Object Lessons

We salute and thank all of those great teachers out there who find engaging activities to get their students back in the seats and ready to learn for another school year. If you’re a teacher, you know all too well the challenges we face keeping our students engaged and interested. If we’re not careful, it’s easy for some students to disappear into their surroundings and become that “invisible kid.” This segment featured two demonstrations from our Science of Leadership workshop for teachers that use elements of the science demonstration as a metaphor for learning. Oh, by the way, teachers shared their best first days of school activities on our Facebook Fan page this week.

Take a look at our First Days of School Kit with ideas for getting your students excited about the year after the first bell.

One of the most popular activities is Mentos and Diet Coke Geysers to ring in the new school year. There are many teachers who use hands-on science activities to get kids excited about learning and bring it home to the dinner table. Read the experiment page for more information on these Back to School activities.

Here are two science activities to use to welcome students back to school and learning. The first is a lesson in refraction that teaches kids about being an invisible student. The teacher demonstrates how students can be invisible using Vanishing Jelly Marbles and the index of refraction. By just changing the background by adding a little food coloring, a good teacher can help their students stand out.

This demo teaches us how to become invisible… just blend in with your surroundings. But it’s equally amazing to see how invisible objects become visible by just changing the surroundings. Add a few drops of food coloring to the bowl of water and stir. The once invisible Jelly Marbles now stand out again the different colored background.

Over the years, there’s been lots of talk about the dangers of “invisible students.” This is an amazing way to get students to talk about the dangers of just blending in… becoming invisible… seeming insignificant or believing that no one cares.

The following poem is offered by a wonderful friend and a well respected authority in student leadership development, Dr. Earl Reum. Earl often used the Jelly Marbles as a way to get students talking about the “Invisible Kid.”


[An open letter from the “Invisible Kid” to graduating seniors]

I’ve wanted to write this for a long time but never seemed to have the right words. I am a “nobody.” Some people might think of me as an Invisible Kid. I have never thought of myself as a “leader.” I know who the leaders are in my school. I know all of the “popular” kids. I even have lunch with them once in a great while when I’m invited to join their table.

Sometimes people call us “nobodies” the silent majority. We just sit back and let everyone else make decisions for us. It’s not that we don’t want to get involved. We just don’t know how to get involved. We timidly raise our hand in class to volunteer to help on a special project, but we usually get passed over for someone who is more of a “leader” type. But sometimes we do get picked! I cannot tell you how special that makes us feel. We don’t get picked very often, but when we do, we’re supposed to feel privileged… and we generally do.

When we get the courage enough to actually participate in an activity, we kind of feel out of place and uncomfortable. Those who do try to make us feel more at ease and human-like will forever have our deepest thanks.

I guess I don’t mind being a nobody. I stay out of the way of the popular kids so they don’t have a chance to make fun of me. I’ve never been elected to anything. I’m not a trouble-maker in class, and I even get pretty good grades. I’m only special to me and to those few who are close to me. The spotlight never shines on me – I can only watch it glimmer from afar.

I want you to know that even though I’m a nobody, I have important things that I want to tell everyone. I really do want to share my hopes, my dreams, and my special talents with anyone who is willing to receive what I so desperately want to share.

I hope that by telling you this you will take a moment to stop and think about us nobodies. I think that there are lots of nobodies in the world. Maybe the two boys who killed the students and teacher at Columbine High School thought of themselves as nobodies when they were younger. Maybe they didn’t feel like they belonged to anything. I think they probably felt alone, not loved, and certainly not needed. Maybe that’s why they made up that gang and wore black trench coats and wrote poems about hate and death. Maybe that was their way of trying to reach out and belong to something. I don’t know why they did those terrible things, but I know that the sadness in my heart has caused me to take another look at my life.

That’s why I don’t want to be a nobody any more. Last night I made a promise to myself and my family to think of myself as a “somebody,” even if it makes me feel uncomfortable. I am going to raise my hand more. I am going to volunteer more. I am going to share my hopes, my dreams, and the things that make me special with anyone who will listen… even if it make me feel embarrassed. Please help me to be a somebody by continuing to invite me to be on your team, to sit at your lunch table, to get more involved in school activities. I might say “no,” but please keep asking. Someday I will have the courage to say “yes.” You can make a difference in my life.

- The Invisible Kid

(Written by Dr. Earl Reum)