Example- If I were to have a survey in the school about the lunch food, asking if it were good, bad, or somewhere in the middle. I wouldn't do multiple surveys about it and not include certain people in the high school or even middle school about it for example boys and girls. I would take one collective sample of the entire high school and middle school, and if that wasn't possible, I would get 25 middle school boys, 25 middle school girls, along with 25 high school boys and 25 high school girls, in order to get an even fair sample. In order to make the sample as random as possible, I would do a random number generator with either my calculator or a website using three digits. From 001-how ever many boys/girls there are in the middle school/high school. Then I would get 25 different triple digit numbers for each of the 4 categories I made, middle school boys, middle school girls, high school boys and high school girls. Then I would get a list of each of the categories and match the numbers to the names of the students. I would make sure to get the random numbers before to make sure that the survey was random.