– Bowls

– Craft Feathers

– Water

If you don’t have the feathers on hand, paperclips or pompoms also work, though the effect is most dramatic with the feathers! You can also cut feathers in half for a normal-sized bowl. If using full-sized feathers, you should switch to a small pan.

How To:

Place the bowl of water on a table. Place the feathers next to them.


Present this challenge to your kiddos:

How many feathers can you get to float on top of the water at the same time?

Take predictions from all your kiddos. If you have a class or large group, graph them!

Then let your kiddos get to work!

(All the feathers will float.)

Present this challenge to your kiddos:

What happens when you pile all the feathers up in one spot?

(The pile will tip over before the surface tension breaks.)

Science behind the fun:     

Water’s surface tension is the biggest factor in why so many feathers can float on its surface. Individual molecules of water look like a “Mickey Mouse” head — the head is an oxygen atom and the ears are hydrogen atoms. The end of the water with the hydrogens is slightly positive and the opposite end is slightly negative.

The positive end of one water molecule forms hydrogen bonds with the negative end of another water molecule. A network of hydrogen bonds across the surface of the water creates a surface tension that is strong enough to support dozens of feathers (and even critters like mosquitoes and running basilisk lizards)!



– Half a bag of cranberries

– Water

– Baking Soda

– Printer Paper

– Homemade Pen (To write your message. Paintbrush, cottonswab, or something with an absorbent tip.)

How To:

Have an adult or teenager boil the cranberries in about 3 cups of water for 15-20 minutes.

Be sure to put a lid on the pan since the small pockets of air that help cranberries float can make them explode as they cook. If you listen, you will hear some of them popping.

Crush the cooked berries and push the liquid through a sieve or colander to collect the concentrated cranberry juice.

 Most cranberry juice from the grocery store is diluted with water, corn syrup and other juices and won’t work as well.

Let the juice cool and pour it into a casserole dish or cake pan that the paper you’re writing your messages on will fit into.  

If your cranberry juice seems thick and syrupy, add a little water (maybe half a cup.)  It has to have enough water in it so that it will soak into the paper.

To make your invisible ink, add a few teaspoons of baking soda to about 1/3 cup of warm water and dissolve it as well as you can.  

Don’t worry if you can still see some baking soda.

Dip your homemade writing tool into the baking soda solution and write a message on your paper.

               It may take a little practice, so don’t get frustrated.  You’ll get the hang of it!

Let your message air dry, or speed things up with a blow dryer.

To reveal your message, float and then submerge your paper in the cranberry juice and see what happens!

Science behind the fun:   

Cranberries contain pigments called anthocyanins (an-tho-SY-a-nins), which give them their bright color.  In nature, these pigments attract birds and other animals to fruit.  This is important because animals eat the berries and spread plants seeds from one place to another.

These pigments, called flavanoids, change color when they come in contact with acids and bases.  Cranberry juice is very acidic, and the pigment is red in acids.  When you add it to a base, it turns purple or blue.  Baking soda is a base, so your baking soda message will turn blue when it comes into contact with the pigments in the cranberry juice.  Eventually, when enough cranberry juice soaks into the paper, it will dilute the baking soda and make the paper acidic, turning the pigment back to red and your message will disappear!

There are over 300 kinds of anthocyanins which are found in many fruits and vegetables including blueberries, red cabbage, grapes and blueberries. Scientists think they may have many health benefits and some researchers are even making organic solar cells using flavanoids!

Ask your kiddos what other juices they think will work to reveal secret messages? If you use lemon juice, does your ink turn a different color?