Maryland Math 7.DS.A.2.b
The Standard
- 7.DS.A.2
- Use data from random samples to make and evaluate estimates or predictions about a population.
Generate and compare multiple random samples of the same size and use the variability across samples to assess how reliable an estimate or prediction is.
Maryland College and Career Ready Standards for Mathematics (2025) · MAKE SENSE OF STATISTICAL INQUIRY.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students take several random samples of the same size from one group. They make the same kind of estimate from each sample and compare how much the estimates change. They use those differences to judge how much to trust a prediction about the whole group.
What Mastery Looks Like
- A student calculates an estimate from each sample and compares the results. They explain that estimates close together give more reason to trust a prediction than estimates that vary widely. They do not treat any one sample as an exact answer.
Common Misconceptions
- Students may expect every random sample to give the same result. They may compare differences among individual responses instead of differences among sample estimates. Some forget to return and mix items between samples, so later samples come from a changed group.
How to Assess It
- Exit ticket: Three samples of 20 students give 20%, 25%, and 20%; another three give 10%, 25%, and 40%. Which set gives you more confidence in its prediction, and what numbers support your answer?
Lesson moves
Ways to Teach It
Put 30 red and blue counters in a bag; draw 10, return and mix them, then repeat five times and compare red percentages.
Ask: Five samples of 20 give 30%, 35%, 30%, 60%, and 55%. How sure are you of a 30% prediction?
Deal pairs cards with three 20-person sample results, 35%, 40%, 35% versus 10%, 40%, 65%; race to pick the steadier estimate.
Collect slips on tomorrow's lunch choice; sample five slips three times, returning them between draws, then compare predictions with the full count.
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Related Standards
- 7.DS.C.5.b
Use a known or estimated probability to evaluate whether the number of outcomes in a given number of simulation trials is reasonable.
- 7.DS.A.2.a
Use data from a single random sample to estimate an unknown characteristic of a population.
- 7.DS.A.2
Use data from random samples to make and evaluate estimates or predictions about a population.
- 7.DS.C.6
Develop and use probability models to find probabilities of events and compare them to observed results.
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