6.12.C

Math6th Grade

The Standard

summarize numeric data with numerical summaries, including the mean and median (measures of center) and the range and interquartile range (IQR) (measures of spread), and use these summaries to describe the center, spread, and shape of the data distribution

Texas Essential Knowledge and Skills for Mathematics

Teacher's field guide

What This Standard Means

What Students Need to Do

Students order a data set and calculate several values that show what is typical and how much the data varies. They compare the mean and median, then compare the range and IQR. They use those results with a graph to describe balance, clustering, skew, or extreme values.

What Mastery Looks Like

Given a data set and a dot plot, a student accurately finds all four summaries. The student identifies a typical value, compares overall and middle spread, and explains any skew or extreme value.

Common Misconceptions

Students may find the median before ordering the values or divide the sum by the wrong number of values. They often confuse IQR with range or subtract the wrong quartiles. They may trust the mean even when one extreme value pulls it away from most of the data.

How to Assess It

Give students the data set 2, 3, 4, 5, 6, 10. Ask them to find the mean, median, range, and IQR, then describe the center, spread, and shape in one sentence.

Lesson moves

Ways to Teach It

  1. Have students place data cards on a floor number line, then mark the mean, median, quartiles, range, and IQR with colored tape.

  2. Show two dot plots with equal means but different spreads, and ask, "Which group is more consistent, and what evidence proves it?"

  3. Play Summary Match: teams pair data sets, box plots, and cards listing mean, median, range, and IQR.

  4. Use class commute times to compare a typical trip, variability, and the effect of one unusually long commute.

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