This is a fun activity that reinforces the need for geography and results in a very handy reference for the students. The map has all 50 states outlined and the students must use the top to indicate how each section of the United States' territory was acquired. The states are listed alphabetically so it requires the students to know the state names. This will also help students learn the state names if they do not already know them.
20 minutes (If they know their states)
50 minutes (If they don't know their states)