The Museum Blog

Category: Junior Science

Walking Rainbow Experiment

Walking Rainbow

By Meredith Brustlin, CMNH Educator

We share a lot of different science experiment projects at CMNH. Many of these experiments have instant results - things like vinegar and baking soda bubbling, popcorn dancing, and invisible ink appearing. What I really like about this “walking rainbow” experiment is that it takes some time to see the results (as in, it takes hours to fully see the results!) Although it may not be as exciting in the moment, it is a perfect experiment to practice making predictions and thinking like a scientist. It really gives young scientists time to think and hypothesize and even change their guesses throughout the day. 

To make your own rainbow you will need:

  • 7 clear cups--these can be glass or plastic, just make sure they are perfectly clear (not colorful)
  • Water
  • 6 paper towel pieces (this could be three large sheets cut in half, or 6 of the little half sheets)
  • Primary colors of food coloring or liquid watercolor

Set-up:

  1. Set out the 7 cups in a line
  2. Fill cups 1, 3, 5, & 7 about halfway with water
    1. Leave cups 2, 4, & 6 empty
  3. Fold your six paper towel pieces in half lengthwise and then in half again. Take that long skinny strip and fold it in half so that it can stand up in the cups (pictured above)
  4. Invite young scientists to help you add some food coloring to the cups. 
    1. Ask them--what is the first color of the rainbow? Red! Add about 6 drops of red food coloring to the first cup.
    2. What is the second color? Orange! That cup is empty though, so we will skip that one. 
      1. Add yellow to the 3rd cup
      2. Skip the 4th cup (green)
      3. Add blue to the 5th cup
      4. Skip the 6th cup (purple)
      5. Add red to the 7th cup and ask your scientists why they think you may have done that…!
  5. Next, carefully place your paper towel pieces in between each cup so that they are resting in the colorful water. 

That’s it for set up! Now it’s time to think like a scientist!

Ask your young scientists…

  • What do you think will happen with the cups?
  • Why do you think we left some cups empty?
  • What do you know about primary colors?
    • How do you think what you know about primary colors (that they make secondary colors) will come into play in this experiment?
  • What do you notice is already happening with the paper towel pieces and the water?

Feel free to have your scientists write or draw what they are seeing!

This experiment will take awhile to completely finish and make the rainbow design. It’s a good idea to either do this experiment at night before bedtime, make some predictions, and then wake up and see the walking water rainbow. You could also do this experiment first thing in the morning and then watch it change all day long!

Have fun making a walking rainbow and thinking like scientists! 

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Science Magic: Secret Rainbow

By Colie Haahr, CMNH Educator

This project is fun and easy, and only requires a little bit of prep ahead of time. Kids will enjoy magically making a rainbow appear by adding water to a paper towel. This activity is fun on its own, or it can be set up as an experiment that they can try a few times and record the results.

Materials Needed:

Paper towels
Washable markers
Black permanent marker
Cup for water
Tray or plates 
Pipette, eye dropper, or small spray bottle
Optional: Different brands of markers, highlighter, permanent markers, pencil, pen 

Directions:

  • Prep ahead: This project requires some prep ahead if you want to create a truly “secret” rainbow! You can create more sheets for kids to try as you go if they enjoy the activity! -Use a water based marker to create a rainbow on a paper towel. Remember ROYGBIV! 

-Thin lines work well for this- do not make them too thick because you need to cover them with permanent marker

-Use a black permanent marker to carefully draw over each line, hiding the colorful lines under the dark lines. 

-Optional: create shapes that are different colors, and use the same process to cover them with permanent markers. 

-Optional: Set up the color mixing part of the activity the same way coloring two circles next to one another in primary colors (red and yellow, red and blue, and yellow and blue)

  • Place one of the prepared paper towels onto a plate or tray that is okay to use for an art project (it may get marker ink on it!), with a cup of water and pipette or spray bottle
  • Make a prediction- ask: what do you think will happen when we add water?
  • Ask kids to slowly add some water to the picture
  • The rainbow will “magically” appear when the water based marker dye spreads, and the permanent ink stays in place
  • Try the same method with color mixing, or the colors hidden behind shapes
  • Let the artwork dry completely, and some of the dye will stay on the paper towel once it dries. Too much water can cause the color to wash out completely
  • Alternatives: This also works with a tray of water, and kids can carefully place the paper towel in the water and watch what happens. 

-Make an experiment! To make this a true experiment, try using different types of writing utensils, like markers, pens, pencils, highlighters, etc., and testing each one to see if water changes anything. Compare different brands of markers to see which ones work the best. Make predictions and write down the results! 

Science Information: 

For this activity there were two types of markers used, and they were made of different types of dyes or inks. One was water soluble, and one was not. If the experiment went as planned, the water based markers should have spread color out on the paper towel. These markers have dye that is water soluble, which means that it is able to dissolve in water. 

The permanent marker has a different kind of ink or dye, and it is not water soluble, which means that water will not wash it away. The permanent marker is alcohol based, so it will dissolve in alcohol. If rubbing alcohol were added to the paper towel, it may have changed the permanent marker, but because only water was added, the permanent marker stayed the same.  

The paper towel also played an important part in making this activity work. This activity did not work well on other types of paper, like card stock and copy paper. Paper towels are absorbent, and designed to absorb or suck up liquids. If the paper were waxed paper or something similar, the water would bead up into droplets because water molecules like to stick together. Water molecules still like to stick together on paper towels, but there are tiny air pockets in paper towels, and a soft cellulose material that allows the water molecules to move around the paper towel together. 

References:

https://indianapublicmedia.org/amomentofscience/how-do-paper-towels-absorb-water.php

https://www.thebestideasforkids.com/surprise-rainbow-activities/

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Oil & Water Mixing Sensory Bottles

by Meredith Brustlin, CMNH Educator

There are so many fun experiments that you can try using oil and water. If you’re at the grocery store and thinking about picking up one or two items for your young scientist’s “at home chemistry station” I definitely recommend a big jug of vegetable oil. It’s inexpensive, easy to find, and can be used for tons of science! 

This experiment does some simple MESS FREE oil and water mixing. I especially like this experiment because the experiment itself is quick and can be done over and over again. Some people also use these oil & water mixing bottles as sensory bottles - moving the oil back and forth and watching the gentle waves it makes can be very relaxing. Who doesn’t need a bit of extra relaxation these days? 

Here’s how to make your own:

Materials needed:

  • Small jar or container with a lid that can be securely screwed on (plastic or glass--although with very young scientists you may want to go the plastic route and duct tape that lid on there, too!)
  • Vegetable oil
  • Food coloring

Directions:

  • Fill your container halfway with water
  • Pour vegetable oil in to fill up the rest of the container
    • Watch and see what happens!
  • Add a drop of red or blue food coloring
    • Watch closely again! 
  • Tightly secure the lid of your container
    • Optional: add some duct tape to really seal it in place
  • Watch as the oil and water in your bottles become completely separate and the drop of food coloring makes its way down to the water portion of the bottle - it will take a few seconds. 
  • Gently move the bottle around and watch the oil and water - they stay separate when moved gently
  • SHAKE your bottle! Really shake it and watch as the water and oil temporarily mix
    • What else happens?!
  • Watch closely again as the oil and water slowly separate

The Science: 

There are several different science “happenings” going on during this experiment. 

Oil & Water:

  • Your scientist’s will notice that the oil and water do not mix! The oil sits on top of the water and it always will. This is because water and oil are immiscible. Basically what this means is that water molecules only want to hang out with other water molecules and the same with oil molecules. The oil sits on top because it is less dense or less heavy than the water so it happily floats on top of it. 

Primary/Secondary Colors:

  • Vegetable oil is used for this experiment because it is yellow in color. If we used another kind of oil, like baby oil, you would have to purchase oil based food coloring which isn’t all that easy to find. The yellow vegetable oil automatically gives us one of our primary colors. Blue or red food coloring is added so that when you mix, you get a secondary color! 
    • There are lots of great books you can read/find videos of online to explore primary/secondary colors, check out: 
      • Mouse Paint by Ellen Stoll Walsh
      • Mix It Up by Herve Tullet
      • Monsters Love Colors by Mike Austin

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Science Magic: Glitter & Soap

by Colie Haahr, CMNH Educator

Try out this easy experiment with materials you already have at home! This experiment is about surface tension, and you can make glitter magically “dance” in a bowl of water! The reaction is quick, but kids love trying it more than once. This could be a good experiment to try before transitioning to water play, which always seems to be a hit! 

Materials Needed:

Shallow bowls or plates
Water 
Glitter, Pepper, Cinnamon, or All Spice 
Toothpicks or Q-tips
Dish Soap
Toothpaste
Cooking Oil

Directions:

  • Set up: Pour water into bowls, and place a very small amount of all of the other liquids into lids or small bowls. A pitcher of water is helpful to reset the experiment. The experiment works best with dish soap, but using a few other substances makes it more of a true experiment, where some will work and some will not. 
  • Optional: have a pencil and paper handy to record observations and hypotheses 
  • Pour about a teaspoon of glitter into one bowl of water, and a teaspoon of whatever spices you would like to use into another. You want the glitter and spices to cover the surface of the water
  • Make an observation: what happened when we poured the glitter/spices into the bowl? 
  • The glitter or spices stay on the surface of the water because they are hydrophobic, and they do not dissolve in water like salt or sugar would. 
  • Carefully dip the end of a clean toothpick or Q-tip into the liquid dish soap, and poke it right into the center of the bowl
  • Make an observation: What happened to the glitter/spices? The glitter should move quickly to the edges of the bowl when the soap touches it. 
  • Repeat the process with the toothpaste, cooking oil, hand soap or anything else you decide to try
  • Optional: write down what happens each time you try the experiment 

Science Information: 

Water molecules like to stick together, so when you pour a drop of water onto something non-porous, like waxed paper, the water beads up. Kids usually can picture this happening on a windshield when it’s rainy the rain drops stick together and roll down the windshield. 

When you pour water into a bowl or plate, this creates surface tension. 

During the experiment, you observed that the glitter and spices in the water bowls stayed right on top. Even though water molecules like to stick together, they do not always stick to other things, like the glitter and spices. The surface tension of the water allows these small particles to float on top! They do not dissolve, and usually, they do not get saturated and sink. 

When you added different substances to the water, some caused the glitter and spices to move away to the sides of the bowl. Now experiments can be tricky, and they do not always work perfectly, but the oil should have made no changes to the water bowl, and the soap and toothpaste should have caused the particles to move. The substances that made the glitter and spices had something in common: they all clean things! 

Dish soap should have worked the best, and this is partially because dish soap has molecules (teeny tiny parts) that are BOTH hydrophobic and hydrophilic. Wait, that would mean the soap molecules repel water molecules, and attract or bond to them! This is true, soap is a good cleaner because it can pull things like oil out of water because of the hydrophilic properties, like when we wash dishes, dish soap helps to get rid of grease and oil that water alone can’t remove. 

When the soap touched the water bowl, it broke the surface tension of the water, and that’s why we could see the glitter and spices move. Soaps and cleaners are designed to break down the surface tension of water. This helps make them good cleaning tools. When you added the dish soap or toothpaste to the water it broke up the surface tension. The water molecules, however, want to stick together and maintain that tension, so they move away from the soap, carrying the glitter and spices with them! We can see the reaction because there are particles floating on the top of the water. The water would still move when soap is added, but because it is clear, we can’t see it. The glitter and spices help us see what’s happening in the water bowl! 

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Science MAGIC: Invisible Ink!

By Meredith Brustlin, CMNH Educator

I was THRILLED to find this invisible ink recipe. Many invisible ink recipes involve holding dried lemon juice messages over a candle and almost setting pieces of paper on fire. Luckily, this recipe doesn’t require any heat and is totally safe---besides the slightly strong scent of rubbing alcohol. However, with it warming up outside--this would be a great outside project!

Here’s how to make your own heat-free invisible ink:

Materials needed:

  • 2 medium-size glass containers (I used Pyrex liquid measuring cups)
  • Q-tips
  • Paintbrushes
  • Paper (white paper works best, you could also use cardstock!)
  • Table covering
  • Cookie sheet/craft tray
  • 1 tsp powdered tumeric
  • ½ cup rubbing alcohol
  • 1 Tbsp baking soda
  • ½ water

Directions (prep):

  • Set up your experiment area, whether inside or outside, by protecting the area with some kind of covering. This could be a plastic tablecloth, trashbag, or some other non-absorbent material. 
  • Place a cookie tray in the experiment area
  • Gather all other materials and have them on hand. 

Directions (activity):

  • Tell little ones that today you will be experimenting with invisible ink! 
  • Invite them to help you mix 1 Tbsp of baking soda into ½ water in one of your glass containers
    • Mix until it is mostly dissolved and keep mixing throughout your experimenting--it doesn’t dissolve all that quickly. 
  • Have little ones draw on their paper with the baking soda solution using q-tips
    • It will be hard to see what they are drawing! They can try writing words or just doing abstract doodles. Anything will be fun to find using the invisible ink decoder!
  • Put aside the drawings to dry
  • While they are drying, make your “decoding” solution
  • Mix 1 tsp turmeric powder into ½ cup of rubbing alcohol 
    • The turmeric solution will stain hands and surfaces--so be careful while mixing and using this solution. At least it won’t set your house on fire, right?! 
  • Once your papers are completely dry, place them on the cookie sheet and paint over them using the tumeric decoding solution. What happens?!?!
  • Watch your paper change color more as they completely dry. 

The Science: 

(For younger scientists):

  • Explain that the baking soda “ink” is changing color because it reacts or changes when it meets the turmeric solution. There is an ingredient in the turmeric that changes the baking soda to that very deep purple color when they meet! 

(For older scientists):

  • Turmeric is a ph indicator. This means that it will change the color of different substances when it interacts with them to show us what their ph is. 
    • Ph tells us the acidity or basicity of items. 
    • Basically, substances go through a chemical reaction when they “meet” a ph indicator and that causes them to change color. 
    • Think about a traditional baking soda and vinegar experiment - they combine and erupt! That is because baking soda is a base and vinegar is an acid. If we tested the ph of vinegar it would be a very different color than the ph of baking soda. 
  • When you paint over the baking soda papers with turmeric, we are seeing that deep purple appear because that is the color that baking soda changes when it interacts with a ph indicator. 

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Science Magic: Dancing Popcorn!

by Meredith Brustlin, CMNH Educator

We had a great response to our last science magic video (Plastic Bag Polymers!) so decided to share another! 

Dancing Popcorn Magic

Materials Needed:

  • Clear plastic cup/tall container or clear glass cup/jar
  • White vinegar
  • Baking soda
  • Unpopped popcorn
  • A spoon

Directions (prep):

  • Fill your clear container about ½ way with water
  • Put vinegar in a smaller cup
  • Put baking soda in a small cup with the spoon
  • Place unpopped popcorn in another small bowl

Directions (activity):

  • Tell your young scientists that today you are going to make some popcorn DANCE using science! 
  • Invite them to put a few spoonfuls of baking soda in the cup of water and stir until it has fully dissolved
  • Add a couple spoonfuls of popcorn to the baking soda mixture. Is it dancing yet? 
    • Make a hypothesis--what will happen when we add the vinegar?
  • Carefully & slowly add the vinegar to the baking soda solution
  • What happens?!
    • You will notice that the popcorn starts to DANCE!

The Science:

  • This science magic is created using a simple chemical reaction. When we add vinegar & baking soda together--we create carbon dioxide. 
  • You can see this at work! If you watch the popcorn carefully, you’ll notice that it gets covered in little bubbles and it bobs up and down. 
  • Those bubbles are made of carbon dioxide. As they collect on the popcorn, it lifts the popcorn up to the top of the container. Once it is at the top, some of those bubbles “pop” and bring the popcorn back down again. 
  • This up and down motion is what makes the popcorn look like it is dancing!

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Shiny Penny Experiment

By Colie Haahr, CMNH Educator

We were surprised by how excited kids got about cleaning pennies when we offered this experiment as a drop in STEAM activity at CMNH! It does seem like a magic trick when you first see the pennies getting shinier almost instantly. 

This experiment is a good way to practice making predictions and observations, and it’s an easy one to do with materials that are available at home! For kids learning about money and currency, this is a great way to practice counting and recognizing the different coins as well. 

Materials:

  • Table cover of some kind (a trash bag works!)
  • Several pennies
  • Other coins- quarter, nickel, dime, coins from other countries if available 
  • Vinegar 
  • Salt
  • Bowl of water
  • Bowl for vinegar and salt mixture
  • Q-tips
  • Paper towels 
  • Optional: lemon juice, soapy water, other liquids you would like to experiment with

Directions:

  • One way to set this experiment up is to use a muffin tin or small bowls to offer several different liquids for kids to try. A small pallet for paint works well, too! 
  • Put the coins on a surface you do not mind getting messy- plastic plate, paper towel, or directly on the table covering, but you will want some paper towels or dish towels nearby
  • Allow kids to experiment with the materials to see what would work best to clean the different coins by dipping the coins in the liquid, and brushing them with a q-tip
  •  Ask what they think will work best, and why?
  • After some experimentation, guide them toward the vinegar or lemon juice mixed with salt. The salt works as a mild abrasive, and the acid in the vinegar and lemon juice react with the pennies to make them shiny and new looking
    • Important: rinse the pennies in water after cleaning them if you would like to keep them nice and shiny! They will oxidize and turn green otherwise. 
    • Fun fact: this is what happened to the statue of liberty, and why it looks green today! Kids did not dip it into a bowl of vinegar, but the statue is copper, and it turned green because of oxidation over time. 
  • Ask why the acidic liquids cleaned the pennies, but not the other coins? What is different about them? The pennies are a different color because they are made of a different material: copper!

What’s Happening? 

 Pennies are made of copper, and copper is shiny, but over time it becomes tarnished and appears black or brown because of copper oxide, which is created when copper bonds with oxygen. Acids mixed with salt help break down the copper oxide on the penny. Vinegar may remove actual dirt from the pennies and other coins because it works well as a cleaner! 

Extensions: 

Science Bob offers a few more experiments you can try using the same materials.

Scientific American offers some ideas for different liquids to use, and a more in depth explanation and method for advanced experiment-ers.

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Learning About Symmetry

The Children’s Museum of New Hampshire’s Monday science class offered a group of eleven 3-5 year olds a chance to learn and apply the concept of symmetry.

The museum’s Early Childhood and Literacy Coordinator, Meredith Brustlin led the Junior Science Explorers class, offered by the museum on Mondays from 1:30 to 2:15pm.

Meredith first gathered the group together and explained the concept of symmetry using images of butterflies, lions, and houses. Kids were challenged to identify which images displayed symmetry and which did not.

Jrsci1

Following the lesson, the group sat down to a hands-on symmetry activity, allowing them to apply what they had just learned. The kids were given the choice of painting one side of either a butterfly or a bee.

Jrsci2

They were then instructed to fold their papers in half, revealing a symmetrical work of art they were free to take home.

Jrsci3

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