Maryland Math 7.DS.A.2

7.DS.A.2 is a cluster heading. These are the individual standards under it.

• 7.DS.A.2.a

  Use data from a single random sample to estimate an unknown characteristic of a population.

• 7.DS.A.2.b

  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.

01

What Students Need to Do

Students use a random sample to estimate a count, percentage, or average for a larger group. They compare estimates from several samples of the same size to judge how dependable a prediction is.

02

What Mastery Looks Like

If 6 of 20 randomly sampled students ride the bus, a student estimates about 60 bus riders in a school of 200. They know another random sample may give a different estimate and use the spread of estimates to judge how sure they can be.

03

Common Misconceptions

Students may ask only their friends and call that a random sample. They may treat one sample estimate as the exact answer or assume all random samples must give the same result.

04

How to Assess It

Exit ticket: A random sample of 20 from 200 students includes 6 bus riders. Estimate the total, then use estimates of 50, 60, and 80 from three other samples of 20 to judge how reliable your estimate is.

1. 01

   Put 80 red and blue tiles in a bag; pairs draw 10 blindly, estimate the bag's red share, return them, and repeat three times.

2. 02

   Write to the principal: Three random samples of 20 estimate bus ridership at 35%, 40%, and 65%; should one figure be trusted?

3. 03

   Play Estimate Showdown with 30 face-down playing cards: teams draw five, predict the deck's red count, replace, shuffle, and compare three estimates.

4. 04

   Use a numbered list of 100 mock cafeteria orders; generate 15 random row numbers, estimate vegetarian orders, then compare predictions across groups.

• 7.DS.C.5.a

  Use data collection or simulation to approximate the probability of a chance event by observing its long-run relative frequency.

• 7.DS.A.1.a

  Decide whether a sample is representative of a population by explaining how it was selected and how that selection affects the accuracy of conclusions.