In this lesson students draw connections to prior knowledge about probability and use it to interpret data. When the entire sample space is known, the probability of an event can be determined as a ratio of the number of outcomes in the event to the number of outcomes in the sample space. When the sample space is not known, repeating the experiment or simulating the experiment can help estimate the probability of an event by using the ratio of the number of trials in which the event occurred to the number of trials in total.

Students have a chance to work together taking turns explaining their thinking and listening to the explanation of their partners and then critiquing the reasoning they hear (MP3).