Florida B.E.S.T. MA.912.DP.1.5
The Standard
Interpret the margin of error of a mean or percentage from a data set. Interpret the confidence level corresponding to the margin of error.
Florida B.E.S.T. Standards for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students use an estimate and its margin of error to state a plausible interval for a population mean or percentage. They explain confidence level as the long-run success rate of intervals made by the same sampling method.
What Mastery Looks Like
- A student reads 42% with a 3-point margin of error as a plausible range from 39% to 45%. The student explains that a 95% method would capture the actual population percentage in about 95% of repeated samples.
Common Misconceptions
- Students often treat the margin of error as the full width of the interval instead of the distance from the estimate. They may think 95% confidence means 95% of the data fall inside the interval. They may also apply the interval to individuals rather than the population mean or percentage.
How to Assess It
- Exit ticket: A poll reports 54% support with a 4-point margin of error at 95% confidence. Ask students to write the interval and explain what 95% confidence means for the polling method.
Lesson moves
Ways to Teach It
Draw repeated samples of 20 colored counters, use a provided margin of error table, and mark which intervals contain the known bag percentage.
Discuss the claim, “A 95% confidence level means 95% of surveyed people gave answers inside the interval,” then correct it.
Match cards showing an estimate, margin of error, interval, and confidence statement; discard any set with a misleading interpretation.
Use two published poll summaries to write plausible percentage ranges and explain what each confidence level says about the polling method.
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Related Standards
- MA.912.DP.1.4
Estimate a population total, mean or percentage using data from a sample survey; develop a margin of error through the use of simulation.
- MA.5.DP.1.2
Interpret numerical data, with whole-number values, represented with tables or line plots by determining the mean, mode, median or range.
- MA.912.DP.2.2
Use the mean and standard deviation of a data set to fit it to a normal distribution and to estimate population percentages. Recognize that there are data sets ...
- MA.6.DP.1.2
Given a numerical data set within a real-world context, find and interpret mean, median, mode and range.
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