CCSS.Math.Content.HSS-ID.A.2
The standard
Use statistics appropriate to the shape of the data distribution to compare center (median, mean) and spread (interquartile range, standard deviation) of two or more different data sets.
Common Core State Standards for Mathematics
What this standard means
Students need to compare two or more data sets using the right measures for the shape of each distribution. They should know when the mean and standard deviation fit well, and when the median and interquartile range tell the clearer story, especially with skewed data or outliers.
Mastery looks like students choosing measures on purpose, explaining their choice, and using the numbers to make a clear comparison. Common trouble spots are using mean for every data set, ignoring outliers, mixing up range and interquartile range, and describing centers without saying anything about spread.
Ways to teach it
- Give pairs two dot plots with outliers, sticky notes, and calculators, then have them compute mean, median, IQR, and standard deviation.
- Ask students to write which class performed more consistently on two quiz score lists, using center and spread to justify the claim.
- Show two small data sets and ask students to choose the better measure of center and spread in one sentence.
- Compare home prices in two neighborhoods using median and IQR, then discuss why mean price may mislead buyers.
Plan a lesson for CCSS.Math.Content.HSS-ID.A.2
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Related standards
- CCSS.Math.Content.6.SP.B.5d
Relating the choice of measures of center and variability to the shape of the data distribution and the context in which the data were gathered.
- CCSS.Math.Content.HSS-ID.A.3
Interpret differences in shape, center, and spread in the context of the data sets, accounting for possible effects of extreme data points (outliers).
- CCSS.Math.Content.6.SP.B.5c
Giving quantitative measures of center (median and/or mean) and variability (interquartile range and/or mean absolute deviation), as well as describing any over...
- CCSS.Math.Content.6.SP.A.2
Understand that a set of data collected to answer a statistical question has a distribution which can be described by its center, spread, and overall shape.