Samples and Surveys for Kids: Random, Biased and Making Estimates (Grade 7 Math)

Hi, I'm Luna from DoodleBeez. Today we are learning about samples and surveys. When we want to know what a big group thinks, we often cannot ask everyone. So we ask a smaller group instead.

The population is the whole group we want to learn about, like all six hundred students in a school. The sample is the smaller group we actually ask, like fifty of those students.

A good sample is random. That means every person has the same chance of being picked, like drawing names from a hat. A random sample is more likely to look like the whole population.

A biased sample leans one way. If you ask only people leaving a pet shop whether they own a pet, most will say yes. That does not match the whole town, so the result is not fair.

We can use a sample to make an estimate. In a random sample of fifty students, ten chose blue. Ten out of fifty is one fifth. One fifth of five hundred students is about one hundred.

Bigger random samples usually give better estimates. Two random samples may give slightly different answers, and that is normal. Asking two hundred people is more reliable than asking only twenty.

Now it's your turn. In a random sample of forty students, six chose hockey. About how many of the eight hundred students in the school would choose hockey? Pause and try. Eight hundred is twenty times forty, so twenty times six is one hundred twenty.

Great job! Remember, the population is everyone, and the sample is the group you ask. Random samples are fair, biased samples lean one way, and bigger samples are better. Practice samples and surveys in Middle School Math at doodlebeez.com. See you next time!