Research the missions to determine which ones you want your students to build. Father Serra built a chain of 21 Spanish missions. San Francisco Solano is the northernmost mission, while San Diego de Alcala sits near the California-Mexico boarder. Note the suitability of each mission for the project based upon the potential difficulties in duplicating the architecture. Generally speaking, most of the missions have a simple Spanish style most young students can duplicate with simple art supplies.
Pass out the names of missions to students in random order to prevent some students from choosing a popular mission while others lack a choice. Since only 21 missions exist and you may not use all the missions for the project, some children may receive the same mission.
Outline the basic materials for your students to use for the construction of the missions. Two materials dominate this project: cardboard and clay. While clay missions offer a more authentic looking final product, cardboard is easier to work with and more accessible. In fact, one large storage box provides more than enough material to construct the mission.
Research and find the official website for each individual mission. Give these websites to the students for their research. These websites provide important historical information regarding the history behind the missions' construction, important historical events at each mission and the lifestyle at the mission including interaction with Native American tribes.
Print pictures or have your students print pictures of the missions to use as a blueprint for the project. Students need an accurate depiction of the mission in front of them at all times as a model to duplicate the outlay of the buildings.
Assign a due date for the project, and randomly assign days for project presentations. Fit as many presentations you can in a day so the students don't forget any important information while waiting to present.