December 19th marks the 236th anniversary of General George Washington and the Continental Army’s arrival at Valley Forge. Here a tired and ill-equipped army would camp for the winter during one of the bleakest periods of the American Revolution.

In 1777 the Continental Army was exhausted and nearly defeated. The troops were poorly fed and clothed. Disease was rampant and supplies were scarce. The Army had but a single axe to construct the first buildings at the camp, and Congress had no money to pay for new supplies.

Some soldiers deserted. There were even rumors about a plot to replace Washington as commander. The British were just miles away, occupying Philadelphia, the greatest city in colonial America. Everyone worried that the war for independence would soon meet a sad end.

The scene at Valley Forge was so dismal, most of us today can hardly imagine it. And yet, the Army held together. The troops spent the winter training for battle, completing endless drills to improve their skills and technique.

What made them sign up for such misery? The answer can be found in our Declaration of Independence, written just a year earlier by courageous Patriots who took great risks for our country. The Declaration read in part: “We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable rights, that among these are life, liberty and the pursuit of happiness.”

These were the bold ideas from which America was born, and they are the principles that continue to define our nation. They are at the heart of what has made America exceptional.

We owe an incredible debt to those Americans who endured that long winter at Valley Forge and kept fighting for what they believed — just as we are indebted to the millions of others throughout our history who have sacrificed greatly to win and preserve our freedom

Today, unfortunately, we are doing a poor job of passing the lessons of their sacrifice on to the next generation of Americans. We are watching our nation’s memory of the past slip away as we fail to teach our children about American history, including our founding principles and values.

The Department of Education’s recent National Assessment of Educational Progress survey shows how serious this problem has become. Just 20 percent of fourth-graders, 17 percent of eighth-graders and 12 percent of twelfth-graders are at grade-level proficiency in American history.

Only one in three fourth-graders can identify the purpose of the Declaration of Independence.  Less than half understand why George Washington was an important leader in American history.  And most fourth-graders don’t know why the Pilgrims left England.

These results suggest what a terrible job we have done helping the next generation understand our history and the great privilege of being American.

We must do better.  Those of us who understand the importance of passing on the lessons of our nation’s past must find creative ways to tell the American story.

Children’s books can be a good way to introduce young people to American history. As the author of three children’s history books, I have visited classrooms across the country to share the adventures of Ellis the Elephant, my time traveling pachyderm, with four to eight year olds. Most young people I meet are eager to learn and are excited to discover our nation’s pivotal moments.

Interactive online courses, television programs like “Liberty’s Kids,” and educational video games like Oregon Trail can also teach critical history lessons.  And of course, visits to historic sites like George Washington’s home at Mount Vernon or Independence Hall in Philadelphia are wonderful ways to inspire a love for American history.

As we gather with friends and family this holiday season, take a moment to think about the cold, sick, and starving soldiers at Valley Forge who had nothing but rice and vinegar for Christmas dinner in 1777.  And then, take a moment to share their story with the young Americans in your life. We have so much to be grateful for.

Callista Gingrich is the author of Yankee Doodle Dandy, the third in the Ellis the Elephant series for children ages four to eight. She is the president of Gingrich Productions.