The mathematical purpose of this lesson is to introduce the normal distribution as a way to model distributions that are approximately symmetric and bell-shaped. Students are introduced to relative frequency histograms, which are histograms that show the proportion of the entire data set within specified intervals. Students also encounter the term normal distribution, which is a distribution that is symmetric and bell-shaped, has an area of 1 between the -axis and the curve, and has the -axis as a horizontal asymptote. When students articulate the things they notice and wonder about histograms and a curve, they are attending to precision in the language they use to describe what they see (MP6).

Technology isn’t required for this lesson, but there are opportunities for students to choose to use appropriate technology to solve problems. We recommend making technology available.