I would start with the following: "What do we mark with boundaries?"
"What is the importance of the use boundary markers?"
"Should boundary markers ever change? If so, when?"

I would have the students brainstorm the questions with a small group or with partners. We would make a class list on their responses, or they may respond to the questions on an online discussion board through Schoology, where they will be able to give responses to others' answers.
I would expect most of them to come to the conclusion that boundaries can separate and establish what belongs to whom. People use them to mark their own personal property from others' properties.
I would present them with the marker we used in this module as an example. They would probably connect that it is a markers of some sort, but some may think like I did, that it is some sort of cemetery marker.
The students would then examine maps of the U.S. dated from 1781 to 1865 and make notes on what the U.S. was like at the time. Noting states and territories which were added and primary documents such as the treaties and purchases which granted those new lands to the U.S.
This beginning to lead in many different directions. Imperialism can be identified and defined for the U.S. For example, the westward expansion and the clashing with the Native Americans as the nation claims more land. How the lives are affected between the settlers and the Native Americans. The domination of one group over another because of the cultural differences that exist between both groups of people living there.
Another example would be the acquisition of Hawaii because the U.S. needs it for trade. Economically and militarily, Hawaii was a good location to belong to the U.S., so looking at the history of Hawaii before and after the U.S. paths crossed could demonstrate how boundaries can add positive aspects to one group and negative to another.
World War I maps and ethnicities is another way to show why boundaries change and how it can affect the people within those changing boundaries. Examination of the Treaty of Versailles demonstrates how one group feel they have the right to change the shapes and sizes of nations on a continent due the result of a war. These actions don't consider the normal citizens who have to accept the changes with no ability to defend their own opinions about them.
In closing, I would leave students with the thought, "Imagine your parents decided to move to a new county, state or country, in which you have no say. How would that affect you? What adaptations or difficulties might you encounter to this changing of boundaries?" "Are there any positives to a change for you socially?" Respond and support your answers with examples based on some of the things we have discussed through the previous units.

I would start with a document-based inquiry: "What does an American Look Like?" We can look at the Constitution, Declaration of Independence, Birth Certificate, Naturalization Certificate as primary resources. Students can read diary entries from an immigrant, analyze political cartoons of the late 1880's depicting Nativists not happy about the arrival of immigrants. Students can Analyze skyscrapers and bridges of New York City and figure out what they are made of. I would ask questions such as who owned the largest company of steel production in the U.S. at the time and where was his family from? There are so many avenues to lead the students in the direction that immigrants did not have it easy and for them to discover it through primary sources and artifacts would be a great way to do it.

I actually used this photo and that of the sewing machine to have the students review what we have learned about the 19th Amendment and women's roles in the U.S. and other places in the world as part of our distance learning work. I was amazed at how much they could respond thoughtfully to the assignment. It is a good way to review and see what the students are learning after a lesson as much as before. I loved this assignment and I think they did, too, based on their responses.