Big Ideas:
If E is a set, the complement of E consists of those elements which are not in E.
The complement of a set is based on two things: the set itself and a specific universal set.
This lesson builds on students’ knowledge about sets and sample space which were informally developed in seventh grade (7.SP.8a). Complements are frequently useful when it comes to computing the probability of an event. Students are initially asked how to find the number of ways a pair of dice could show different values. An easy way to answer this question is to find the complement of this event: the number of ways the dice could have the same values.
Vocabulary: complement, universal set
Special Materials:
It would be helpful for the teacher to have a pair of dice, but not necessary for the students to each have a pair.
Lesson plan