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Our weekend science fun was inspired by a book, Becoming Invisible: From Camouflage to Cloaks by Carla Mooney. Most children's books about camouflage talk about how animals try to blend into their environment. This book is very different. It is about how modern engineers and scientists are trying to make the fictional invisibility cloak from the Harry Potter books into a reality. For a review of the book and links to more science books, see our sister blog, Wrapped in Foil.

Camouflage and invisibility are two very different things. Camouflage is the use of color or other aspects of appearance to help an object blend with its environment.

“Optical camouflage” is a form of camouflage which uses projectors to display scenes of the moving background onto special reflective cloaks. From the right angle, it is impossible to tell where the cloaked person (or object) is standing because he or she seems to be part of the background images. If the viewer isn’t in line with the projectors, however, the illusion doesn’t work.

Invisibility, on the other hand, is changing the way light reflects or refracts when it hits an object and thus preventing the light from reaching our eyes. We literally can not see an object that is invisible.

Becoming Invisible: From Camouflage to Cloaks tells how scientists have been able to bend electromagnetic waves that are near relatives of visible light (see Exploring Light and its Relatives Part I and Part 2) with special man-made materials called metamaterials. Using metamaterials made of metal and fiberglass, scientists have been able to develop "cloaks" that bend microwaves and infrared light around an object, hiding it from detection. Very cool!

Activity 1. Hiding with color - camouflage for younger children

Read one of the books suggested below to introduce the idea of camouflage.


  • Fabric swatches of different colors and designs
  • Painter's blue tape (doesn't leave a residue when it is removed, but it is more expensive) or masking tape
  • Suitable area to play hide and seek, indoors or out

You might want to sort the children into teams if you are working with a large group. You will need enough swatches of fabric so that each child or team can hide a few different swatches. Make loops of tape with sticky-side out and then apply a few to the back of each swatch. Now select a child/team to be the hider. They will hide the swatch in plain sight in the play area by taping the swatch to items while the other children, who will be the seekers, close their eyes or wait in another area. When the hiders have applied their swatch, have the seekers come look for it. Once they have found it, change roles. The goal is to find a background object that matches the color close enough that the fabric is difficult to see, and thus takes longer to find.

Activity 2. Hiding with color- camouflage for older children


  • Paper
  • Art supplies such as markers, crayons, colored pencils, etc.
  • Painter's blue tape (doesn't leave a residue when it is removed, but it is more expensive) or masking tape (optional)
  • Suitable area to play hide and seek (optional)

For older children, have them create their own camouflage patterns for different settings. You could also have the children do the hiding activity (1), but substitute their own designs on paper for the fabric swatches. Or figure out an experiment to test the effectiveness of various camouflage designs.

Activity 3. Making glass "disappear"

We don't need high tech metamaterials to make an object invisible. We can hide a piece of Pyrex® glass by immersing it in a material that has a similar index of refraction, Wesson® oil.


  • small Pyrex® glass bowl
  • A larger glass bowl
  • Wesson® oil or baby oil, or a mix of the two

Place the smaller bowl inside the larger bowl. Fill them both with Wesson® oil, baby oil, or a mix of the two. Once covered with oil, the smaller Pyrex® bowl should disappear from view.

See a similar activity using a Pyrex® stirring rod and explanation from Exploratorium

Activity 4. Make jelly marbles disappear in water

Obtain some jelly marbles from science supply stores, for example from Steve Spangler. Soak the jelly marbles overnight in water. Then fill a clear glass container with water. When you drop in the soaked jelly marbles, they will disappear.

Jelly marbles are polymers that absorb water. When they are swollen with water, they have the same index of refraction and disappear when you place them in water.

This video shows examples of both of the index of refraction activities:

Isn't that amazing?

If you try any of these activities, be sure to let us know what you find out.

Related camouflage links:

Children's books about camouflage (title links go to Amazon):

Hiding in Deserts (Creature Camouflage)
by Deborah Underwood

My review

Animal Planet Weird and Wonderful: Show-Offs (Animal Plant Weird & Wonderful) by Margaret McPhee is not just about camouflage, but all the ways animals use color.  My review

Where in the Wild?: Camouflaged Creatures Concealed... and Revealed by David Schwartz and Yael Schy, with photography by Dwight Kuhn My review

Where Else in the Wild? is a enchanting combination of poems by David M. Schwartz and his wife, Yael Schy, and photographs by Dwight Kuhn. My review

How to Hide an Octopus and Other Sea Creatures (Reading Railroad)
by Ruth Heller

How to Hide a Butterfly and Other Insects (Reading Railroad) by Ruth Heller.

What Color Is Camouflage? (Let's-Read-and-Find-Out Science, Stage 2) (Let's-Read-and-Find-Out Science, Stage 2) by Carolyn B. Otto and illustrated by Megan Lloyd

Today our post was inspired by the picture book A World of Bugs (Comparing Bugs: Acorn Read-Aloud) by Charlotte Guillain.

Way back when I started this blog, I purposely chose the title "Bug of the Week" for the long-running Wednesday feature because I knew I would want to include spiders, pill bugs, and other creepy crawlies, as well as insects.  A World of Bugs shows children the range of arthropods and other invertebrates that are often called "bugs." It tells what their features are, how they grow, where they live, and how they move. It is filled with huge, full color photographs that are very attractive. On the last page, the book also has some suggestions for activities to do before and after reading the book.

Identification of insects and their relatives requires careful observation of their anatomy.

Insects are part of the phylum of animals called Arthropoda.  All arthropods have:

  • supporting skeleton on the outside, called an exoskeleton
  • bi-lateral symmetry, which means if you draw a line down the center the two sides will be symmetrical
  • jointed appendages
  • segmented bodies
  • specialized appendages, like antennae

The major arthropod classes can be separated by comparing their number of body regions, legs, and antennae.

Activity 1. Compare various creatures to discover features using live arthropods to observe, pictures and rubber or plastic models to explore. Give the children free explore time at first, and then start to encourage them to observe the following features:

Arachnids are the spiders, ticks, mites, scorpions and their relatives

  • Have 8 legs
  • Have 2 body regions, the cephalothorax (literally head-thorax), and abdomen

Spiders have 6 or 8 eyes at the front of the cephalothorax. Spiders' mouthparts are called chelicerae and typically end in a fang. Around the mouth are the pedipalps.

For detailed information about spider anatomy, see Invertebrate Anatomy Online, the Garden Spider.


The Isopods, which are called pillbugs, roly-polies, or wood lice, and other common names, have:

  • 12 legs
  • 2 antennae (one pair small)

Pill bug activities for kids

Centipedes and millipedes

  • Many legs per segment
  • Many segments
  • One pair of antennae

Millipedes have 2 pairs of legs per segment.

Centipedes have one pair of legs per segment. (Photograph from Wikimedia).

Insects have:

  • Three body parts:  head, thorax and abdomen
  • Six legs
  • One pair antennae
  • Many adults have wings, but not all

Next time we will discuss how to recognize the major groups of insects, the orders.

A World of Bugs by Charlotte Guillain

Reading level: Ages 4-8
Paperback: 24 pages
Publisher: Heinemann-Raintree (August 1, 2011)
ISBN-10: 1432955063
ISBN-13: 978-1432955069

Book was provided by publisher for review purposes.


Welcome to the October 21, 2011 edition of STEM Friday.

Are you looking for Science, Technology, Engineering or Math children's books? Then you've come to the right place. We've gathered some of our favorites here today.

My submission today is the wonderful new book that is coming out next week, Coral Reefs by Jason Chin.

Have you ever been so immersed in a really good book that you felt like you entered a new world? In Coral Reefs, Jason Chin's illustrations show a young reader experiencing just that when she picks up a book about coral reefs and enters a glorious underwater world of corals, fish and sea turtles. 

If you saw Jason Chin's previous book, Redwoods, you will know what an interesting mix of highly imaginative watercolor illustrations (fictional) and straight nonfiction informational text to expect. This time the reader picks up a book at a city library and is swept into what the author calls the "cities of the sea," the coral reef community. The reader floats through every underwater scene, carrying her (magically intact) book with her.

Having the child reader in every illustration gives interesting advantages. It gives a clear sense of scale. It also draws the real reader into each scene, giving him or her more of a sense of participation. Finally, each illustration is so different from what is typical of a nonfiction book that it really takes time to study and absorb all the nuances. Clearly, capturing the child's imagination has a potential to lead to greater understanding of the topic.

Jason Chin thoroughly researched his book, including a visit to the coral reef off the coast of Belize. His personal experiences give to real "depth" (sorry) to the book. Did you know that some sea turtles graze on the sea grasses that grow in lagoons that form behind coral reefs? Or that the biggest fish in the world, whale sharks, visit the reef in Belize each spring to feed on eggs of spawning fish? Coral reefs are dramatically important sources of food for ocean dwellers.

In the backmatter, Chin has included a page about how coral reefs are threatened and some straightforward ways to help prevent further loss. He also shows a cross section of the structure of a typical coral reef and more information about the symbiotic relationship between the coral organisms and algae that live inside them.

Even the endpapers are informative, showing soft pencil sketches of various sea creatures with their names and size ranges underneath. It gives the feel of sketches in a nature journal.

This book would be a fabulous addition to a unit on marine habitats or to tuck into the bag for a read at the beach. Follow up with a visit to your local aquarium or even better, a snorkeling trip to a real coral reef.

Reading level: Ages 4-8
Hardcover: 40 pages
Publisher: Flash Point (October 25, 2011)
Language: English
ISBN-10: 1596435631
ISBN-13: 978-1596435636

Secret of the Sleepless Whales…and More!
by Ana Maria Rodriguez

at Ana's Nonfiction Blog

My Friend the Box Turtle
by Joanne Randolph

At NC Teacher Stuff

Tracks in the Sand by Loreen Leedy is now out of print,

but is available as an iBook

at Loreen Leedy Books

How They Croaked: The Awful Ends of the Awfully Famous
By Georgia Bragg
Illustrated by Kevin O’Malley

at Simply Science

Explore Simple Machines!: 25 Great Projects, Activities, Experiments (Explore Your World series)
By Anita Yasuda

at Nomad Press

Garbage: Investigate What Happens When You Throw It Out with 25 Projects (Build It Yourself series) by Donna Latham

at Wrapped in Foil

Uninvited Guests: Invisible Creatures Lurking in Your Home (Tiny Creepy Creatures)
by Jennifer Swanson

at Chapter Book of the Day

If you would like to participate in STEM Friday in the future, go to the new STEM Friday blog for more information.

Book was provided by publisher for review purposes.