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New revolutionary war picture book.

Selene Castrovilla's recently published book, Upon Secrecy (Calkins Creek, ISBN# 978-1-59078-573-7), is a beautifully illustrated and suspenseful story that details the Revolutionary War era in the United States. With art by Jeff Crosby and Shelley Ann Jackson, your students will learn about the strategic techniques of George Washington and the story of the Culper Spy Ring:

George Washington needed spies.

Information about the enemy was vital.

Learning British military plans was his only chance to level the advantage the redcoats held.

Washington's army had become something to reckon with. They'd gone from fighting for survival to spotting fear in their enemy's eyes.

Still, the British army was larger.

Better equipped.

Virtually impossible to outfight.

Washington knew that wits, not weapons, held the key to ultimate victory.

The general's problem wasn't finding information. Captured British soldiers often spilled secrets. Redcoats would appear on their own, prepared to turn traitor against their king. Even civilians offered to spy for a fee. But could Washington trust them?

For two years the Culper Spy Ring provided Washington with information, but they often took a very long time to get their information to the general. Upon Secrecy follows them through British territory and back again in a dangerous race to report back to Washington without being detected.

A segment that would be very interesting to young historians and scientists alike is the page devoted to "sympathetic stain," or invisible ink:

With good reason, Abraham Woodhull was nervous about writing messages to George Washington. It was a great relief when Washington received a gift of the invisible ink called "sympathetic stain" (together with the substance that would make the ink visible again) in November 1778. The stain came from John Jay, a member of the Continental Congress. Sir James Jay, John's brother, had invented it three years earlier in England. Washington wrote Benjamin Tallmadge: "I should be glad to have an interview with Culper myself, in which I would put the mode of corresponding upon such a footing that if his letters were to fall into the enemy's hands, he would have nothing to feat, on that account." (Excerpts used with permission from Boyds Mill Press).

Castrovilla goes on to explain that as the war went on, the Americans became savvier with the ink. At first, they were writing letters to one another using only invisible ink, thus creating an apparently blank page that would be very suspicious if it landed in enemy hands. Washington eventually convinced his spies to use the ink only in between lines of letters about family or other matters of little interest to opposing spies.

Write Your Own Invisible Ink Messages

After reading Upon Secrecy, have your students write their own Revolutionary War spy messages in invisible ink! Here are two recipes provided by

Invisible Ink Made with Baking Soda What you need:

* Baking Soda

* Paper

* Water

* Light Bulb (heat source)

* Paintbrush or Swab

* Measuring Cup

* Purple Grape Juice (optional)

What to do:

There are at least two methods to read your message when you use baking soda as an invisible ink.

1. Mix equal parts water and baking soda.

2. Use a cotton swab, toothpick, or paintbrush to write a message onto white paper, using the baking soda solution as "ink".

3. Allow the ink to dry.

4. One way to read the message is to hold the paper up to a heat source, such as a light bulb.

The baking soda will cause the writing to turn brown.

5. A second way to read the message is to paint over the paper with purple grape juice. The message will appear in a different color.


1. If you are using the heating method, to avoid igniting the paper don't use a halogen bulb.

2. Baking soda and grape juice react with each other in an acid-base reaction, producing a color change in the paper.

3. The baking soda mixture can also be used more diluted, with one part baking soda to two parts water.

4. Grape juice concentrate results in a more visible color change than regular grape juice.

Invisible Ink Made with Lemon Juice What You Need:

* Lemon or Lemon Juice

* Sunlight or Heat Source

* Paper

* Paintbrush or Stick


What to do:

1. Squeeze lemons to obtain their juice or use bottled lemon juice.

2. Use the juice as ink by applying it to a stick or paintbrush and writing on paper.

3. Allow the paper to dry.

4. When you're ready to read your invisible message, hold the paper up to sunlight, a light bulb, or other heat source.

5. The heat will cause the writing to darken to a pale brown, so your message can now be read.

6. Another way to read the message is to put salt on the ink while it's still wet. After a minute, wipe the salt off and color over the paper with a wax crayon to reveal the message.


1. Experiment with other juices. Orange juice, vinegar and apple juice all work well.

2. A cotton swab makes an excellent disposable paintbrush.

3. The writing turns brown because the weakened paper burns before the rest of the paper. Be careful not to overdo your heating and set the paper on fire!

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Title Annotation:Grades 1-3; Upon Secrecy
Publication:Curriculum Review
Geographic Code:1USA
Date:Dec 1, 2009
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