This page practices deciding whether a survey sample is random or biased (7.SP.1-4). Example: "Is this sample random or biased? A survey is done by picking 50 names at random from the whole school list."
Click on the image to open the Random and Biased Samples PDF. Print it to use the worksheet. The answer key is on page 2.
Random and Biased Samples
Use this free 7th grade math worksheet from Teaching Squared. Find more in Statistics and Probability Worksheets and 7th Grade Math Worksheets.