As the presidential campaigns of Barack Obama and Mitt Romney move into full swing, both men have to stake out positions on many issues. From health care to economic revival to the environment, Obama and Romney make promises and set priorities.

So far, one of the defining issues of 2012 has been immigration: How should the U.S. handle illegal immigration and possible immigration reform?

Put the issue into perspective for your students by providing them with resources on immigration in U.S. history. The U.S. today rests on the heritages of many different peoples — from a land populated by native peoples to a country founded by colonists to a world power that both welcomed and restricted immigration at different times.

Where to start? Historian Alan Gevinson outlines the ups and downs of immigration from the 1870s to the 1920s in Ask a Historian, but remember that the arrival of newcomers to North America began much earlier! Who were the ancestors of prehistoric peoples like the Mississippi Moundbuilders? Check out the website Peopling North America for some theories.

The original English colonists may not have seen themselves as immigrants, but they were certainly newcomers to an already-peopled land. A lesson plan on Jamestown explores early contact between English and the Powhatans.

Other early Americans came to the English colonies against their will. Atlantic Slave Trade and Slave Life in the Americas: A Visual Record can introduce students to the brutal separation of Africans from their homelands and their sale to the Americas. What regulations managed the slave trade? When was it stopped in the U.S.?

As the U.S. developed and its boundaries expanded, national views on immigration have shifted multiple times. In Lesson Plan Reviews, we look at lesson plans on Asian immigration through Angel Island, Jewish immigration, and living conditions in tenements after the Civil War. (For more on Jewish immigration, visit our Beyond the Textbook feature.)

Browse more than 100 Website Reviews for primary sources on the lives of immigrants throughout U.S. history. Or find suggestions for teaching about immigration in Ask a Master Teacher.

On August 6, 1945, the United States dropped the first atomic bomb used in warfare on Hiroshima, Japan. On August 9, 1945, the second atomic bomb struck Nagasaki. This age of nuclear warfare began less than a month after the first test of the atomic bomb in the New Mexican desert, and Robert Oppenheimer, leader of the Manhattan Project, later recalled, "There floated through my mind a line from the Bhagavad-Gita in which Krishna is trying to persuade the Prince that he should do his duty: 'I am become death: the destroyer of worlds.'"

The decision to use atomic bombs against Japan is considered among the most controversial decisions in military history. Multifaceted arguments examining the causes and effects of that decision began before the bombs fell, continued in the immediate aftermath, and have not yet ended, and we probe them from the perspectives of military, political, social, and cultural history. Was the bombing justified? Did it hasten the end of the war?

Primary and secondary educational resources support an emphasis on multiple perspectives and historical thinking in approaching units about Hiroshima and Nagasaki. The following suggestions are directed toward high-school and some middle-school classrooms.

Hot Topics: Hiroshima on the History News Network gives educators an overview of historiography and arguments behind the bombing. Among them, Peter Kuznick, Associate Professor of History and Director of the Nuclear Studies Institute at American University, addresses past and present perspectives in The Decision to Risk the Future . . . Harry Truman, the Atomic Bomb and the Apocalyptic Narrative. Sean Malloy, assistant professor of history at the University of California, Merced, Four Days in May . . . Henry L. Stimson and the Decision to Use the Atomic Bomb follows the political rationale and chronology leading to Hiroshima.

For students, Steven Mintz's Digital History essay, The Controversy Continues in the unit America at War: World War II, brings the discussion into the present day using argument about the presentation of an Enola Gay exhibit at the Smithsonian as a starting point to examine different points of view about Hiroshima and Nagasaki.

Help students become familiar with the arguments and look for their own conclusions through materials digitized at the Truman Library. A special collection focuses on The Decision to Drop the Bomb and includes documents totaling almost 600 pages covering the years 1945-1964. Secondary source materials include an online version of Truman and the Bomb: A Documentary History, edited by Robert Ferrill. Among the primary source documents, the press release by Henry Stimson of August 6, 1945 includes an accompanying Lesson Plan for exploring the text and implications of that release.

The Gilder Lehrman Institute teachers' module on World War II incorporates a lesson plan on the Manhattan Project and a link to Was it Necessary?, a site highlighting this question and related primary documents exploring it.

The New York Times provides a lesson plan on He's the Bomb! with a look at Hiroshima 60 years later.

Edsitement Lesson Plans for grades 9-12 offer a balanced perspective on the decision to drop the bomb, linking to resources on the debates over the decision to bomb, Japan's decision to surrender, and arguments about the effect of the bombing on Japan's decision. Edsitement suggests assessment standards for its lessons and related resources for extending the lessons.

YouTube offers various historical footage of the bombing as well, but teachers will want to carefully screen videos and download them to a flash drive for accuracy and for age-appropriate coverage. And at the Library of Congress, a selected search of cultural collections and the Prints and Photographs online catalog also yields a multitude of photographs of the aftermath of the bombing and of further text-based resources.

The Hiroshima Peace Memorial Museum is a multifaceted look at the bombing and destructive effects on individuals and on the world. The museum presents a message of peace through a look at the horrors of war through survivor histories and exhibits on Hiroshima City and Japan before and after the atomic bombing. The museum directs many online materials toward elementary school ages, and is also well worth a visit from all ages for a conversation about how we remember, interpret, and use our historical past.

As Ronald Takaki writes in The Lessons of Hiroshima, "The history of this world-shattering event offers us lessons on war, race, leadership, reason, judgment, and the importance of cross-cultural understanding. Those who do not know history, a philosopher warned, will be doomed to repeat it. Hiroshima is a past that is not even past, and we ignore it at our peril."

On May 26, 2009, President Obama nominated Judge Sonia Sotomayor to replace retiring Justice David Souter on the U.S. Supreme Court.

The Senate Judiciary Committee is likely to hold hearings on her nomination in July and to seek a confirmation vote in Congress before the August 8 summer recess. If confirmed, Sotomayor would be the third woman on the Supreme Court and the first Hispanic justice, but how important are gender and ethnicity to the selection and approval process?

In The New Republic, columnist Tom Goldstein sketches the likely arguments for and against her confirmation. "Overall, the White House's biggest task is simply demonstrating that Judge Sotomayor is the most qualified candidate, not a choice based on her gender and ethnicity. The public wants to know that her greatness as a Justice is informed by her personal history and her diversity, not that it is defined by those characteristics," he points out.

At the top of her class at Princeton University and editor of the Law Journal at Yale University, Judge Sotomayor has been a prosecutor, private litigator, trial judge, and appellate judge. For more than a decade, she has served on the United States Court of Appeals for the Second Circuit which incorporates Connecticut, New York, and Vermont. As an appellate judge, she reviews decisions of District Courts for errors of law. Read sample cases she has adjudicated during her tenure as a member of the court's three-judge panel.

The judicial system is perhaps the least understood and most complicated among the three branches of U.S. government to explain and to teach.

To place Sotomayer's appellate experience in the context of the judicial system, visit U.S. Courts for an explanation of the structure of the American court system and the responsibilities of each kind of court. The Wikipedia entry, United States Courts of Appeals, also gives a helpful overview of the role of the functions of these courts and of how to find further documented information.

In a review of books about the Supreme Court at History News Network (HNN), historian Peter Hoffer explains why we need to understand the history of the Supreme Court. (Search HNN for other current and historical analyses of the role of the Supreme Court and specific decisions.) Hoffer writes,

. . . a history of the Court is essential because its operation is often obscure. The complexity of the cases the Court chooses to hear and decide cannot easily be explained to lay people. The deliberations of the Court are kept secret and cloak its operation and thinking from our inspection. The arcane language of the law in its opinions adds another layer of incomprehensibility to the Court's operation.

And at Annenberg Media, the course Democracy in America includes the unit The Courts: Our Rule of Law, stressing how "we depend on our courts and the rule of law to resolve conflicts between citizens and the government and between and among citizens." Lesson plans, primary source documents, critical thinking activities, and readings explore the importance of the American legal system and of the role of courts in defining law.

A teacher-authored history of the Supreme Court, produced in conjunction with PBS station Thirteen/WNET New York, offers educators and advanced learners a series of essays giving a comprehensive overview of the Court, of major decisions, and of their context. Lesson plans link to online resources and incorporate primary source documents requisite to implement each lesson plan.

The Thirteen/PBS website evolving from the PBS series on the Supreme Court also includes multimedia presentations on court justices and major events in the Supreme Court's history. Lesson plans, games, interviews, and discussion guides provide a variety of materials for classroom use.

Other useful resources include

The Supreme Court Historical Society explains how the Supreme Court works and its history.

Landmark Supreme Court Cases provides teachers with a full range of resources and activities to explore the key issues of major court decisions and presents the Constitutional concepts around which they evolve.

The Supreme Court's website includes current as well as historic information and materials.

A recent NHEC Blog entry brought up the topic of online textbooks for students. But how about an information-laden U.S. history textbook for teachers full of primary sources and multimedia presentations?

Annenberg Media and a consortium of educational agencies have developed such a resource, America's History in the Making, for middle and high school teachers of history, social studies, and related classes. It's intended as a professional development tool to deepen educators' knowledge of American history.

America's History in the Making is a thematically-organized approach to 800 years of American history, providing content and teaching methods for classroom use and integrating video, text, classroom activities, and web-based interactive activities. The content, according to Annenberg's explanation of the course, reflects ". . . a diversity of characters, personas, and geographies, with the goal of providing a broad and accurate account of the history of the United States from pre-contact through present day."

Twenty-two units comprise the course. Sixteen half-hour videos segmented into overviews of an era, biographical capsules, and historiographic discussion supplement various units, and content units each cover an era of American history from pre-Columbian America through the present day. Chapters are available as downloadable PDFs, a timeline contextualizes the events of each era, and a chart demonstrates linkages to individual state standards.

Start at About the Course for an explanation of course goals, content, materials, and organization. Then, before moving into content, check out How to Use This Site which further explains structure and resources.

The quarterly journal of The Gilder Lehrman Institute of American History, History Now, is always excellent, and the issue focusing on the American Revolution is no exception.

What's there? An in-depth ideological and historiographic look at the Revolution and materials to help teach about the era—including, but not limited to the following:

Three short original documentaries, featuring historian Carol Berkin and produced by NBC Learn, explore Thomas Paine, Women in America, and the Articles of Confederation.

Lesson plans From the Teacher's Desk include units on Revolutionary Propaganda for high school; Colonists Divided: a Revolution and a Civil War for middle school; and a look at The Boston Massacre for elementary school students.

Isaac Kramnick and Woody Holton are among the scholars who offer in-depth background essays on aspects of the Revolution and the era under Historian's Perspective.

September 17, 1787, was a seminal day for America.

Earlier that year in May, spurred by inadequacies in the Articles of Confederation and the need for a strong centralized government, 55 delegates representing 12 states met in Philadelphia to "take in to consideration the situation of the United States, to devise such further provisions as shall appear to them necessary to render the constitution of the Federal Government adequate to the exigencies of the Union."

In secret proceedings, the delegates argued and debated throughout the summer about the duties, responsibilities, form, and distribution of power in the new government. Then, on September 17, 39 of the delegates signed a four-page document— a Constitution consisting of a Preamble and seven articles proposing the infrastructure of American government. Then the ratification process began.

Constitution and Citizenship Day, initiated in 2005 and observed on September 17, commemorates the event and mandates that each educational institution receiving Federal funds conduct an educational program on the Constitution on that day. Background papers, interactive lesson plans, and supporting materials abound for classroom use. We mention only a few below.

At the Department of Education, the Teaching American History Team at the Office of Innovation lists several essential resources from Federal institutions, including FREE, the Department of Education's own internet library highlighting 28 diverse teaching resources on the Constitution.

The Teaching American History team also annotates the varied resources of the National Archives and Records Administration (NARA) including high resolution scans of the original signed Constitution with transcripts and factual support.

The National Constitution Center in Philadelphia describes its facilities as the only museum devoted to the U.S. Constitution and the story of We, the people. But for those too far away to visit, the museum offers extensive materials for educators, including the Interactive Constitution, enabling keyword and topical exploration of the Constitution as well as analysis of landmark Supreme Court decisions interpreting the Constitution.

Have you attended iTunes University? The National Constitution Center is among the organizations presenting free audio files related to all aspects of the document and its meaning. Listen online or download We the People Stories where experts present ideas on everything from today's relevance of the Constitution, to talks about George Washington, the relationship of the Constitution to the Olympics, and presidential elections— few topical stones are left unturned. (This series is also available via podcasts.)

Do you know which Article of the Constitution created Congress or what the powers of Congress actually are? In its Capitol Classroom, the U.S. Capitol Historical Society challenges visitors to take a quiz to test Constitutional knowledge. Tiered levels offer questions appropriate to 8–11-year-olds through the Constitutional Scholar level.

Among its many resources, the Bill of Rights Institute offers a variety of educational resources free of charge. Weekly eLessons provide 20-minute discussion guides for middle and high school history and government teachers. Educating the Next Generation, a blog, highlights classroom applications and current resources.

The Library of Congress provides a consolidated listing of resources for teachers, including primary sources, lesson plans, Stories for Kids from America's Library, and links to American Memory Collections.

The National Endowment for the Humanities educational site, EdSITEment, consolidates comprehensive resources for teaching about the Constitution, amendments, and the people who made it happen. From lesson plans (K–12) to webography, from biographies and bibliography to teaching with art in the classroom, EdSITEment's presentation of resources offers a wealth of materials to deepen our understanding and approaches to teaching about this document and its meaning.

EdSITEment's inclusion of materials for elementary and middle school students is particularly valuable. A few of those resources are highlighted:

The Preamble to the Constitution: How Do You Make a More Perfect Union? helps students, grades 3–5, understand the purpose of the Constitution and the values and principles explicated in the Preamble.

The Constitutional Convention: What the Founding Fathers Said, designed for 6–8th graders, looks at transcriptions of debates of the Founding Fathers to learn how differences were resolved.

The Constitutional Convention: Four Founding Fathers You May Never Have Met is designed for 6–8th graders and introduces lesser-known key players in the development of the Constitution.

A roundtable discussion published in Common-place, the interactive, online journal, includes eight paired essays in which historians, political scientists, journalists, and lawyers examined the uses and abuses of the Constitution in contemporary American political affairs. Jill Lepore, Jack Rakove, and Linda Kerber are among the discussants.

The Social Studies and History resources of Annenberg Media: Learner.org include the Emmy-Award-winning series The Constitution: That Delicate Balance . In this series of free, video-on-demand presentations designed for high school and above, key political, legal, and media professionals engage in spontaneous and heated debates on controversial issues such as campaign spending, the right to die, school prayer, and immigration reform. The resources emphasize the impact of the Constitution on history and current affairs. The Annenberg Newsletter highlights additional resources.

Landmark Supreme Court Cases provides teachers with a full range of resources and activities to support the teaching of the impact of cases such as Marbury vs Madison, Plessy vs Ferguson, and Brown vs. Board of Education. Background summaries of individual cases and questions for three different reading levels are graded from the highest to those appropriate for ESOL students. Resources include many case-specific short activities and in-depth lessons that can be completed with students.