The video shows bacteria doubling everysecond. Later in the video, the narrator says, "Just one bacterium,dividing every 20 minutes…" This video is sped up so that 1 secondcorresponds to 20 minutes. The goal is for students to initially graph thenumber of bacteria versus time in seconds (a graph that corresponds to thetime-lapse video), and later graph the number of bacteria versus time inminutes (a graph that corresponds to how the bacteria grew in real time).