You don't have to look far to see how important music is to modern American life. Young people (as well as adults) talk about music, listen to music, download music, remix music, share music, and define themselves by music. In classrooms across the country, MP3 players and pop-tune ringtones give students' musical tastes away (and get them in trouble). But has music always been this personal, portable, and repeatable?

Ask your students to think back. Do they remember a time when music wasn't something you could own? When they, someone in their family, or someone they knew didn't have an MP3 player—or a CD, tape, or record player?

Before the birth of the recording industry, you could buy sheet music and learn how to perform musical pieces for yourself—but that was it. An individual performance was ephemeral, literally once in a lifetime.

When the recording industry took off, music became an object. Now you could buy and trade moments in musical time, preserved forever. You could listen to artists who lived far away from you, whom you might never see live. You could listen to your favorite performances again and again. You could even sell music, without having to worry about arranging performances. One song sung once by one artist could earn money for months or years to come. Sound become solid, something that could be passed from hand to hand—and preserved.

On May 10, 2011, the Library of Congress launched its National Jukebox, an online archive of more than 10,000 recordings from 1901–1925. According to the website, Library of Congress staff worked throughout 2010 to digitize this massive collection of Victor Talking Machine Company recordings (Victor, now RCA, is one of the oldest record companies in existence, according to the Library of Congress's blog entry announcing the launch of the Jukebox).

You can browse the recordings by vocal artist, composer, lyricist, language, place or date of recording, target audience, label, category, or genre. And if you find some music you'd like to remember? Add it to your playlist in the site's pop-up player. Now you can listen to it while you browse other sites, email it to yourself to listen to later, or share it with others on social media sites or by embedding it in a blog or website.

While exploring the Jukebox is entertaining in its own right—I just spent two minutes listening to humorous singer Burt Shepard trying to lure a lost cat home—it also makes invaluable primary sources easily accessible.

Teaching about the rise of ragtime and jazz? Make a playlist of famous (and less famous) songs and artists and share it with your students.

How about the invention of the airplane? The Haydn Quartet's "Up in My Aeroplane" can give students an idea of the romance and novelty of flight six years after the Wright Brothers' first successful test run.

World War I? "Hooray, the war is over!" sings Harry Lauder in 1918; months earlier, baritone Reinald Werrenrath remembered the U.S.'s debt to Lafayette and to embattled France.

Pick a time period, a genre, an artist, a word—and go looking! There's something in this storehouse to accompany almost any topic from 1901–1925, if you look hard enough. Use the recordings to grab your students' attention—or ask them to analyze or compare music and lyrics. What do the words (if you choose a vocal piece) say? What emotions does the piece seem to seek to evoke? When was it recorded? Where? Who audience did the composer, artist, or publisher have in mind?

Finding music by topic can be difficult, as none of the pieces have transcriptions, but a little creative searching should leave you with at least a handful of catchy new sources to play with. Watch for more to come—the Library of Congress adds new content monthly, and it hopes to provide content from other Sony labels, such as Columbia and Okeh, in the future.

History teachers have long asked students to create timelines to help conceptualize and understand historical events. Student-created timelines were often limited by the space they occupied. Often teachers would have students focus on a few events and ask them to write very small on their notebook paper to squeeze in events. Clever teachers invested in rolls of butcher paper or banner paper to have students create long timelines. But thanks to today's web designers, timelines are no longer limited in space. Using free timeline builders online allows students to see concepts over time without the constraints of paper and a straightedge.

I have always liked using timelines in my classroom to help students see change over time and help students remember chronology (an oft-heard complaint for students of history).

My students have made standard social, political, and economic timelines of eras of U.S. history in preparation for exams. My students have also created the popular timeline of events leading up the Civil War. I thought myself a clever teacher using large rolls of butcher paper for these timelines to maximize the number of events included and student participation. It was not until I sat down to read the new National Curriculum Standards for Social Studies put out by the National Council for the Social Studies that I saw another way for students to create timelines. "Learners demonstrate understanding by using graphic software to create a timeline depicting a scientific idea of the evolution of a technological innovation, and predicting how that idea or technology might develop in the next 10–20 years." (NCSS 57) With this, I began my search for digital timeline-building websites.

A quick search revealed lots of possibilities for creating timelines online for free. I had to spend a little time playing with each one to find the site that would best work for my needs and students. There are sites that are better tailored to elementary students. There are also those that are more powerful, but less user-friendly. This site provides a nice review of the various digital timeline sites available for free. My project required students to create events with years BCE and CE, which limited the sites I could use and may be a consideration in your site choice. You may also wish to consider what types of multimedia features you would like students to be able to embed in their timelines. Some sites offer the ability to embed pictures and videos. Most timeline-building sites allow users to embed their timelines in blogs or other websites, making sharing timelines easy.

Adapting the product recommended by NCSS, I asked students to create a timeline showing the impact of the Scientific Revolution on a specific field of modern science. To go one step further, students were to make some predictions about future developments in that field (i.e. chemistry, geology, meteorology, etc.). My students quickly caught on to the user interface for the timeline builder and in three 45-minute class periods had researched and created a timeline specific to their field of modern science. You can see an example of one student's timeline here. With more time and practice, I believe that my students will become better at creating richer timelines. After they had created their timelines, students were able to view each others' and comment on them. Ultimately, we created a class timeline merging events from each student's timeline to see the broader impact of the Scientific Revolution.

Digital timelines allow teachers greater flexibility and creativity in assigning timeline activities to students over the old paper timelines. They also allow students to collaborate in a way that fosters chronological thinking and in-depth analysis of eras in history. I hope that you will experiment with digital timelines and share the creative ways you use them in your classroom.