Roller Coaster is a handle where the performers are kept nimble by having to incorporate offers from the audience throughout the scene. The goal of the performers is to continue the narrative arc of the scene. Most offers will be helpful to the narrative, others will be zany and destructive.
Containers is a handle that overlaid on an open scene. As the scene proceeds the performers will pick a slip of paper from the container, read it aloud, and incorporate the offer into the scene. Container is audience centered and fun. The handle does challenge narrative as there can be some very sharp turns hiding in the container.
An open scene is the basis of all improv comedy. In short the open scene is improv comedy. The hundreds of structures covered in Learn Improv are there to support the open scene. All performers should be training and assessing their skill set at the open scene. All bow to the open scene.