James Patterson (plaintiff) participated in a truck-driver training course conducted by the Sacramento City Unified School District (defendant). As part of the course, the participants did community service that simultaneously gave them experience loading and unloading flatbed trucks. For one of his community-service projects, Patterson and the other students were told to load wooden bleachers onto a flatbed trailer and move them to another location. The students were not supervised during this activity, and were not instructed regarding how to load the trailer. Patterson climbed onto the trailer and, with another student, helped pull the bleachers onto the trailer while other students pushed from below. When the students on the ground gave a last push to heft the bleachers onto the trailer, Patterson fell backward off it. Patterson sued the school district for negligence, alleging that it had a duty to supervise the community-service activity. The school district moved for summary judgment, arguing that by participating in the course, Patterson assumed the risk of the course’s activities. The trial court granted the motion, holding that assumption of risk barred Patterson’s negligence claim. Patterson appealed.